Preheat your oven to 400°F (200°C).
Prep the veggies: Cut the Roma tomatoes in half lengthwise and remove the stems. Peel the onion and cut it into quarters. Peel the garlic cloves.
Arrange everything on a baking sheet: Place the tomatoes, onion, and garlic in a single layer. Drizzle olive oil over the top, then season with salt and black pepper.
Mix and roast: Toss everything gently so the veggies are coated, then roast for 40 minutes. This is where the magic happens the veggies caramelize and become beautifully sweet and flavorful.
Cool slightly: Once roasted, let the veggies sit for about 10 minutes so they’re easier to handle.
Blend: Transfer the roasted veggies and all their lovely juices into a blender. Add the tomato paste. Blend until smooth and creamy.
Add basil: Stack your fresh basil leaves, roll them up, and slice into thin strips (a technique called chiffonade it sounds fancy, but it’s super easy!).
Serve: Ladle the soup into bowls and top with those fragrant basil strips. That’s it simple, comforting, and ready to enjoy.