Start by chopping the tomatoes into quarters and the bell pepper and onion into bite sized pieces.
Arrange them on a baking sheet lined with parchment paper in a single layer along with the thyme and whole, unpeeled garlic cloves. Sprinkle salt, freshly cracked black pepper and red pepper flakes over them and drizzle olive oil generously over them.
Bake in the oven preheated at 425°F for 40-50 minutes or until the veggies appear slightly golden brown. Remove the baking sheet and let cool slightly. Peel the garlic and remove the skin.
Transfer to a blender jar along with the fresh basil and stock.
Blend for 2-3 minutes until you get a uniform mixture.
Pour into a soup bowl, top with some more fresh basil, a drizzle of olive oil, feta cheese crumbles and some red pepper flakes or freshly cracked black pepper.
Notes
Use ripe, juicy tomatoes for the best flavor. Roma tomatoes, vine-ripened tomatoes, or other flavorful varieties work well.
Cut the tomatoes, red bell pepper, and onion into evenly sized pieces to help them roast at the same rate.
Arrange the vegetables in a single layer on the baking sheet without overcrowding them. This helps them caramelize rather than steam.
Roast the vegetables at 425°F for 40–50 minutes, or until they are tender with lightly browned edges.
Leave the garlic cloves unpeeled while roasting to prevent them from burning. Remove the skins before blending.
Scrape all the flavorful juices from the roasting tray into the blender for a richer, more flavorful soup.
Start with less stock when blending and gradually add more until the soup reaches your preferred consistency.
Add the brown sugar gradually after blending to balance the acidity of the tomatoes without making the soup overly sweet.
Blend the roasted feta with the vegetables for a creamier soup, or reserve it for garnishing if you prefer a lighter texture.
Adjust the red pepper flakes to your spice preference, or omit them completely for a milder soup.
Let the roasted vegetables cool slightly before transferring them to a blender. Blend in batches if necessary to avoid splashing hot liquid.
Serve the soup with crusty bread, garlic toast, grilled cheese sandwiches, or a fresh green salad.
Store leftovers in an airtight container in the refrigerator for up to 3–4 days. Reheat gently on the stovetop until thoroughly heated, adding a splash of stock if needed.