Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper. Add the cherry tomatoes, onion, salt and olive oil and toss until coated.
2 lb cherry tomatoes, 1 yellow onion, 2 tbsp extra virgin olive oil to drizzle, 1 tsp salt
Add the garlic. Roast on the middle rack for 40 minutes, until the tomatoes have burst and are lightly charred.
4 garlic cloves (skin on, top chopped off)
Let cool slightly. Squeeze the garlic out of its skins and add it to a blender with the roasted tomatoes, onion and all the pan juices. Add the coconut milk, ¼ cup broth and basil and blend until smooth. (Or blend in a saucepan with an immersion blender.) Add more broth a splash at a time until the soup is as thick as you like.
½ cup full-fat unsweetened coconut milk, ¼ cup vegetable broth, 1 small handful of fresh basil
If the soup has cooled, warm it gently in a saucepan or in the microwave.
Taste and adjust the seasoning. If your broth was unsalted you may need more salt.
Optional Toasted Bread Step: I like to brush a couple of slices of white bread (sourdough or ciabatta) with olive oil and add it to the veggies in the oven for the last 10 minutes.