Tinned tomato soup gets you through a Tuesday, but roasting fresh tomatoes with whole garlic cloves transforms it into something restaurant-worthy. The high heat coaxes out their natural sweetness, the basil adds a clean, peppery lift, and the croutons make every spoonful interesting.
Why roasting transforms tomato soup
Most homemade tomato soups taste oddly thin, sharp, or watery — and there's almost always one reason: the tomatoes were simmered, not roasted. High-heat roasting drives off excess water, concentrates the natural sugars, and adds a smoky depth from the lightly charred edges. The result tastes more like tomato than tomatoes themselves.
Roasting whole garlic cloves alongside is the second secret. They turn soft and sweet, losing all their raw bite, and squeeze straight out of their papery skins into the blender. Together they make a soup that feels indulgent without any cream — though a swirl never hurt anyone.
- Naturally vegan and dairy-free; gluten-free without the croutons
- Around 240 calories per serving with the croutons
- Freezes beautifully for up to 3 months
- Tastes even better the next day after the flavours settle
Ingredient notes
The right tomatoes for the job
Roma tomatoes (also called plum tomatoes) are ideal because they have a higher flesh-to-juice ratio than salad tomatoes — you get more concentrated flavour and less wateriness. In peak summer, vine-ripened tomatoes from a farmers' market are even better.
Out of season, supermarket tomatoes work perfectly well here. Roasting at 425°F (220°C) coaxes out flavour even from underwhelming winter tomatoes — it's one of the few preparations where slightly bland produce is forgiven.
- Use roughly 2 lbs (900g) for 4 servings
- Halve them lengthwise and roast cut-side up so the juices reduce
- Skip peeling — a high-powered blender handles the skins
Fresh basil only
Dried basil tastes like sad oregano and has no place in this soup. Fresh basil leaves go into the blender at the end so the heat doesn't dull their bright, peppery aroma. A handful more, torn over the bowls just before serving, is what makes this soup smell as good as it tastes.
Garlic sourdough croutons
Don't skip the croutons. They're not garnish — they're texture, and a tomato soup without something crunchy on top feels incomplete. Tearing the bread by hand (rather than cubing it) gives uneven, craggy edges that crisp up beautifully.
Step-by-step method
1. Roast the tomatoes, onion, and garlic
Preheat the oven to 425°F (220°C). Spread halved tomatoes cut-side up on a sheet pan with quartered onion and unpeeled garlic cloves. Drizzle with olive oil, salt, pepper, and a pinch of chilli flakes if you want gentle warmth. Roast for 30–35 minutes until the tomato edges are deeply charred and collapsing.
2. Toast the croutons
Toss torn sourdough with olive oil and a halved garlic clove on a second sheet pan. Slide it into the oven for the final 8 minutes — they should be golden and crisp on the outside but still chewy in the middle.
3. Blend everything silky
Squeeze the soft roasted garlic from its skins into the blender. Add the roasted tomatoes, onion, vegetable broth, and fresh basil. Blend on high until completely smooth — 60 seconds in a high-powered blender, or 2 minutes in a standard one. Add more broth a splash at a time until you reach your preferred consistency.
4. Serve hot with croutons
Pour the blended soup back into the pan and warm gently — don't boil it, which dulls the basil. Ladle into bowls, scatter generously with croutons and torn fresh basil, and finish with a final glug of really good olive oil.
Nutrition and health benefits
Cooked tomatoes are unusually nutritious — the heat actually increases the bioavailability of lycopene, a powerful antioxidant linked to reduced inflammation and cardiovascular benefits. Research summarised by the Harvard T.H. Chan School of Public Health tomatoes guide consistently shows that processed and cooked tomato products deliver more usable lycopene than raw ones.
Combined with the heart-healthy monounsaturated fats from olive oil and the prebiotic fibre from garlic and onion, this is comfort food that genuinely earns its place in a balanced diet.
- Approximately 240 calories per serving with croutons
- 6g protein, 5g fibre, 12g healthy fats
- Excellent source of vitamin C, vitamin K, potassium, and lycopene
Make-ahead and freezing
This soup tastes noticeably better on day two — the basil mellows, the garlic deepens, and everything settles into something more harmonious. Store it in the fridge for up to 5 days, or freeze in single-portion containers for 3 months. Croutons should always be made fresh; soggy croutons are the saddest croutons.
Variations and serving ideas
- Add a swirl of coconut cream or oat cream for a velvety finish
- Stir in cooked white beans for extra protein and body
- Pair with a grilled cheese sandwich or our {{LINK:0}} for a classic combination
- Top with a soft-boiled egg for a light supper
- Add roasted red peppers to the sheet pan for a sweeter, deeper soup
Frequently asked questions
Can I use canned tomatoes?
Roasting fresh tomatoes is what makes this soup special. If you're short on time, use 2 cans (28 oz each) of whole San Marzano tomatoes — drain them, spread on a sheet pan with the onion and garlic, and roast for 25 minutes. The result is still very good.
How do I make it creamy without dairy?
Stir in 2–3 tablespoons of cashew cream, coconut cream, or oat cream after blending. Soaking 1/4 cup of raw cashews in hot water for 20 minutes and blending them with the soup also gives a wonderfully silky texture.
My soup is too thick. What do I do?
Add more vegetable broth, a splash at a time, until it reaches the consistency you want. Avoid adding water — it dilutes the flavour.
Method
- Preheat oven to 425°F (220°C). Spread tomatoes cut-side up on a sheet pan with onion and unpeeled garlic. Drizzle with olive oil, salt, pepper, and chilli flakes.
- Roast for 30–35 minutes until the tomato edges are charred and the garlic is soft.
- Squeeze the roasted garlic from its skins into a blender with the tomatoes, onion, broth, and basil. Blend until silky, adding more broth to reach your preferred consistency.
- While the tomatoes roast, toss sourdough with olive oil and a halved garlic clove. Toast on a second pan for the final 8 minutes until golden.
- Pour the soup into bowls, scatter with croutons, torn basil, and a final glug of olive oil.
Cook's note
Roasting concentrates the tomato flavour — even out-of-season supermarket tomatoes will taste good after 35 minutes at high heat.