Heat olive oil over medium heat in a heavy-bottomed soup-pot or saucepan.

Add onions, celery, and carrots; saute for 10 minutes, or until soft.

Add garlic and continue to cook for about 1 minute.

Stir in tomatoes, peppers and chicken broth; bring to a boil.

Turn down to a simmer and continue to cook for 30 minutes.

Remove from heat and transfer to a blender.

Puree soup in a blender until smooth. Depending on the size of your blender, you might have to do this part in batches.

Season with salt and pepper. Taste for seasonings and adjust accordingly.

Ladle into bowls.

Garnish with chopped basil and serve.