- Preheat the oven to 400 degrees Fahrenheit.

- Cut the tomatoes in half lengthwise and remove the stems.

- Peel the onion and cut it into quarters.

Peel the garlic cloves.

Take a baking sheet and arrange the tomatoes, onions, and garlic on it.

Drizzle olive oil over the vegetables.

Season with salt and pepper, then mix everything together until well combined.

Place the baking sheet in the preheated oven and bake for 40 minutes. Afterward, remove it from the oven and let it cool for 10 minutes.

Transfer everything from the baking sheet, including the accumulated juices, to a blender.

Add the tomato paste to the blender and blend until the mixture becomes smooth.

Stack the basil leaves on top of each other and slice them into thin strips.

Divide the soup evenly into four bowls and garnish each portion with the basil strips.