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Seaweed and Shiitake Marinara Sauce is a simple tomato sauce, bursting with cherry tomatoes and enhanced with nutritious dried seaweed and fresh shiitake mushrooms. It goes superbly well with gnocchi, pasta and even roasted cauliflower. Vegan and low-carb.

heirloom tomatoes – you may use these instead of canned tomatoes in this recipe.
Tomatoes are going strong here in the UK, so let’s talk about tomato sauce.
Tomatoes are one of those fruit-vegetables that are welcome in most any category of recipe – sauce, pasta, gratin, tian, bake, bread, juice, pie, tart (and here’s another one from me), soup, sandwich, salad. Even dessert. And they are a proper cross cultural food; the base of many a sauce – from Italy to India. But we associate them most strongly, perhaps, with sauce. And Italy.
I am here to subvert this slightly. As you would expect.
What’s different about this marinara sauce?
This tomato sauce comes together in just a few, fragrant minutes. And the only chopping required is some garlic cloves, a handful of mushrooms and half an onion. It is bright and clean-tasting; brilliantly-red; and exudes the essence of tomatoes. So far, so normal.
What makes this tomato sauce different is the funky introduction of seaweed and shiitake mushrooms. Don’t think however that this is Asian. Sure, you could probably use it as a stir-fry sauce (cooked down and spiked with soy and ginger). But it is blissfully good spooned over pan-fried gnocchi, silky, cooked linguine – and even golden pieces of roasted cauliflower. To wit: this seaweed and shiitake marinara is not just a flavour boost for plain pasta.
Why seaweed?
I’ve used dried seaweed – from the highly-rated, UK independent online retailer, Indigo Herbs – for its umami and unique flavour. Despite it being a vegan product, just a few grams in this recipe brings an intriguing briney taste of the sea. It is subtle though. You can add more to give a pronounced seafood vibe. But I am going for whisper of the sea rather than foghorn. And besides, I will exhort you to fry up some extra seaweed – straight from the packet – for a light, crispy, salty topping. So good!
The product I use here is “Irish Sea Salad”. It is a delicious, very more-ish, blend of chopped organic dilisk, wakame, sugar kelp, nori and sea lettuce – all sustainably harvested from the pristine waters off the west coast of Ireland. You could also go single source with any other of their own-brand range of seaweeds – such as Irish sea lettuce, sea spaghetti, pepper dulse, wakame, gutweed or kombu. But I think that the salad version is the one most suited to this sauce, and would go in a wide range of recipes.
Seaweed nutrients
Whichever seaweed you go with, know that it will be packed with essential nutrient iodine, which is something that some of us can be quite low in. Most edible seaweeds are also high in beta carotene, phosphorus, B2, B3, potassium, calcium, magnesium, iron, copper and manganese. Seaweed is also fairly high in sodium, so although I say to season with pepper I don’t think you will need to add salt. Let the cooked sauce sit for five minutes, give it a taste, and hopefully you will agree that it is agreeably savory without need of added salt.
Other than seaweed, what’s in this seaweed and shiitake marinara sauce?
Onion
Garlic
Extra virgin olive oil
Optional red pepper – I just had half a one to use up!
Shiitake or other mushrooms
Cherry tomatoes
Tinned tomatoes
Irish sea salad
Chilli flakes, optional
Gnocchi, pasta or roasted cauliflower, to serve
Extra fried bits of shiitake, seaweed and gnocchi to garnish
I realise that the idea of this sounds a bit bonkers, but I know that you trust me. If you fancy winging it though, instead of my recipe why not just add some Indigo Herbs Irish sea salad – or any of the other seaweeds – to your own simple tomato sauce? If your recipe includes dried herbs, maybe leave them out and let the seaweed guide the flavour.

no guesses who got the gnocchi version!
Indigo Herbs is an independently-owned retail site for all things natural health. As well as an extensive range of health products, they have an A-Z herbs and superfoods reference section, a comprehensive natural health guide, recipes (I really fancy these vegan mushroom gyoza), a blog and more.
Do you use seaweed in your cooking? What other kinds of recipes should I make with seaweed?

Seaweed and Shiitake Marinara Sauce
An easy tomato sauce, bursting with tomatoes and enhanced with nutritious dried seaweed and sliced shiitake mushrooms. It goes superbly-well with gnocchi, pasta and even roasted cauliflower. Vegan and low-carb.
Ingredients
- 2 tbsp extra virgin olive oil
- 250 g cherry tomatoes
- ½ onion about 75g
- 3 garlic cloves smashed, peeled and minced
- ½ red bell pepper chopped; about 70g - optional
- 50 g shiitake mushrooms sliced; plus extra for fried garnish
- 800 g best quality canned chopped or whole tomatoes typically 2 tins
- 10 g Irish Sea Salad chopped as needed; plus extra for fried garnish
- Gnocchi to serve (optional)
- Roasted cauliflower to serve (optional)
- 1 tsp chilli flakes optional
Instructions
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Heat the oil over a medium flame in a wide skillet or saucepan. Add the cherry tomatoes and sauté until a few are lightly coloured.
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Add the onion, garlic, pepper and mushrooms, cooking until all ingredients are soft, stirring occasionally - about 10 minutes.
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Pour in the tinned chopped tomatoes. Or use your hands to crush whole tomatoes as you add them to the nascent sauce. Stir in the Indigo Herbs Irish Sea Salad and optional chilli flakes. Let the sauce bubble up to steady simmer. Cook with a lid for 15 minutes, then remove the lid and cook for a further 15 minutes or until the sauce is reduced to your preference. Stir a bit more often as the liquid evaporates. Season with a few grinds of pepper. You shouldn't need salt.
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While the sauce is cooking, chop and roast cauliflower pieces if using this as your base for the sauce. If you are wanting to serve this seaweed and shiitake marinara sauce with gnocchi or pasta, cook this after you have finished preparing the sauce. The sauce is best - like all cooked tomato sauces - after it is cooled a bit.
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For an extra yummy topping, fry up a little seaweed and sliced shiitake in a bit more olive oil. And if serving the sauce with gnocchi, fry some of the unboiled gnocchi in olive oil until lightly golden.
Recipe Notes
This sauce may be frozen. Use within three months.
Serve over your favourite pasta, gnocchi, low-carb shiritaki noodles, or roasted vegetables.
You have managed to pair so many of my favorite things together! Yum!
Thank you so much! Your comment has made my day! I thought it might be a bit of a scary recipe, so I’m glad you are on my wavelength 🙂
Looks delish & lovely presentation, Kellie!
Thank you, Julie. I hope you try a little seaweed in your sauces soon!
How do you continue to make such comforting food so interesting and so different? The depth of flavour is wonderful and the seaweed balance is brilliant.
Thank you so much. I have to try really hard!
😊😊😊
Yummy.
Very creative – delicious!
Thanks so much, Dolly 🙂
My pleasure, dear Kellie.
These are simple and fast to prepare and everyone enjoyed them!
How utterly amazing. Really love the sound of this, it must be so robust and flavoursome. Those photos with the recipe are sublime too! Very inspiring.
Thanks so much, Niki. The small amount of seaweed really delivers so much umami. And fried up make s a great topping for this as well as on a salad 🙂
This is an amazing and more fast to prepare with full of flavor recipe Kellie and it looks soo yummy with more beautiful colored as well…i will trying to make it from your tips…Thanks for sharing….!
An innovative twist on a classic, made diet-flexible! Loved reading this post too. “Foghorn” made me laugh 😂 another amazing way in which you add depth of flavour with nutritious ingredients
This is an amazing and more fast to prepare with full of flavor recipe Kellie and it looks soo yummy with more beautiful colored as well…i will trying to make it from your tips…Thanks for sharing….!