This easy, homemade vegan roasted tomato soup is flavoured with roasted garlic, red peppers (capsicum), onions and the deeply savoury miso!

Roasted tomato soup is a favourite in my house! Over the years of making it I have tweaked the recipe here and there. It began with simply roasting tomatoes and a couple of onions. Then I added garlic and red bell peppers (or capsicums as they are called here in New Zealand).

In my last iteration, I decided to add my new favourite secret ingredient - Miso. This resulted in the best roasted tomato soup I have ever made!

But it's not really a secret because Miso soup is a staple Japanese dish. The first time I tried miso was in a soup. And then I decided to buy a tub.

Miso is a traditional Japanese seasoning that is produced by fermenting soybeans with kōji and salt. It has a rich umami flavour and can be added to sauces, soups, dressings, etc.

To learn more about Miso soup and other Japanese recipes please visit Just One Cookbook.

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What You Need for this Recipe
Making Roast Tomato, Garlic, Red Pepper and Onion Soup
Pro Tips for this Recipe
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📖 Recipe

What You Need for this Recipe

Equipment

This recipe requires a large pot and a couple of baking trays or roasting pans.

Ingredients

Tomatoes - Any variety of tomatoes will do. I like to do a mix of "regular" tomatoes and cherry tomatoes. This is a great way to use up tomatoes that are overripe or on the edge of overripe. This recipe can be made entirely with cherry tomatoes or "regular" tomatoes - basically, just use what you have on hand.

Onions - regular brown onions. But shallots, red onions, or white onions can be used.

Garlic - Again, any variety will do.

Red Bell Peppers/Capsicums - I prefer the red and orange varieties. And if there are other sweet peppers available I will use those instead.

Salt and Pepper to season the vegetables.

Vegetable stock powder or vegetable stock.

Sugar - sometimes you need a bit of sugar to cut the acidity of the tomatoes.

Olive oil for roasting the vegetables. Use the best quality you can.

Miso - I use a savoury mild white miso. If you don't have miso but still want to boost that umami flavour I would season the roasted veg with Aromat.

Optional Extras - a teaspoon of chilli flakes for spicy roast tomato soup

Making Roast Tomato, Garlic, Red Pepper and Onion Soup

Step 1 - Preheat the oven to 190°/375F/Gas Mark 5.

Step 2 - Remove the tomato stems and slice the large tomatoes in half. Peel and quarter the onions. Peel the garlic cloves and slice the peppers removing the seeds and white veins. Place the veggies cut side up in the roasting pans or baking trays.

NOTE - Cherry tomatoes can be added whole to the roasting dish.

NOTE - it is not necessary to peel the garlic, but I like to do it upfront so I don't have to worry about it later. The head of the garlic bulb can be chopped off and the entire bulb roasted as one. The garlic cloves can then be squeezed out at the end of the roast.

Step 3 - Drizzle the olive oil over the veggies. Season with salt and pepper. Roast for 25 to 30 minutes.

Vegetables in a roasting dish with olive oil, salt and pepper.

Step 4 - Place the vegetables into a large pot. Add the stock powder and 1 Litre of water. Bring to a simmer over medium heat. Allow the soup to simmer for about 30 minutes. Taste the soup about halfway through simmering to determine if the sugar is needed. If the soup is tasting a bit acidic add 1 to 2 tablespoons of sugar. Add in the miso once you have finished simmering the soup.

Note - Tomato skins can be removed before the vegetables are added to the pot. However, this is a personal choice. I usually just go full tomato.

Step 5 - Using an immersion blender, carefully blitz the soup until you have reached the desired texture you are looking for. Serve with a side of croutons, some toast or even a grilled cheese sandwich!

Note - If using stock, leave out the stock powder and add a litre of vegetable stock instead.

Note - This soup can be blended in a regular or traditional blender BUT make sure that the blender jug is capable of blending hot liquids and never fill past ¾ full. Hot liquids expand when blended so allow some space for the hot air to escape. Point the opening away from you when blending. Blend at lower speeds.

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Bowl of roast tomato soup with croutons on a blue napkin.

Pro Tips for this Recipe

Use the ripest, best quality tomatoes you can find. The riper tomatoes have a fuller flavour and added sweetness.

Be careful when blending hot soup! Especially if using a traditional or regular blender.

For accurate measuring when it comes to tablespoons and teaspoons, invest in a set of measuring spoons. When in doubt - always use a level spoon or cup measure. My tablespoon measurements are 15 mL and teaspoons are 5 mL.

Ovens: A conventional oven needs to be set at 20°C higher than a fan-forced or convection oven. Oven temperatures are not consistent, the best way to determine if your oven dial is correct is to use an oven thermometer.

Bakeware: Metal bakeware is superior when it comes to baking biscuits, cookies, brownies, muffins and quick bread, scones, cakes. These heat up and cool down faster than glassware. Glassware is heavier, heats up and cools down slower than metal and are more suited for bread puddings, pies, crisps, crumbles and cobblers.

All my recipes are currently tested at sea level.

Storage and Freezing

This soup can be stored in the fridge for up to 3 days, or frozen for up to 3 months. My preferred method for reheating soup is on the stovetop.

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Roast Tomato Soup