Step 1

In a large stockpot, heat the oil over medium-high heat until shimmery. Add the onion, carrot, and celery. Then, add the red pepper flakes and season lightly with salt and pepper. Stir occasionally until the vegetables are just beginning to brown, about 5 minutes. Stir in the garlic for 30-60 seconds more.

Step 2

Sprinkle the flour over the vegetables and stir for 1-2 minutes, or until flour is fully incorporated.

Step 3

Stir in the chicken stock, tomatoes, tomato paste, sugar, 2 teaspoons salt and 1 teaspoon pepper, stirring and scrapping the bottom of the pan for any browned bits (these add flavor).

Step 4

Bring to a boil, then reduce heat to a simmer and cover partially with the lid*. Cook for about 15-20 minutes, or until all the vegetables are very tender, stirring and scraping the bottom occasionally.

Step 5

Remove from the heat. Use an immersion blender to puree the soup in the pot until fairly smooth. (Or, you can transfer the soup in batches to a large blender. Please be careful during this step! Don’t fill the blender full. Cover the lid with a towel and hold securely while blending so the lid doesn’t pop off. Carefully, return the puree to the pot.)

Step 6

Stir in the butter and half and half. Taste and then adjust the seasoning with salt, pepper, or hot sauce to your preference.

Step 7

Ladle the soup into bowls and garnish with croutons, fresh shredded Parmesan cheese, and fresh basil, if desired.