Heat olive oil in a large pot over medium heat. Sauté diced onion and minced garlic until translucent (about 3 minutes).

Add chopped tomatoes and stir for about 5 minutes until softened.

Pour in vegetable broth and bring to a gentle boil. Reduce heat to low and simmer for 20 minutes.

Blend the mixture until smooth using an immersion blender or by transferring to a countertop blender.

Return the blended soup to the pot, season with salt, pepper, and fresh basil. Simmer for an additional 5 minutes.

Serve hot with extra basil or a drizzle of olive oil on top.