Melt butter in a medium saucepan. Add the chopped onion, carrot, celery and garlic, cover and cook over moderately high heat, stirring occasionally, until the vegetables are just beginning to brown, about 5 minutes.

Sprinkle the flour over the vegetables and stir over low heat for 1 minute, or until the flour is fully incorporated.

Add the chicken stock, tomatoes, red peppers, tomato paste and sugar and bring to a boil. Cover partially and cook the soup over moderate heat, stirring occasionally, until the vegetables are tender, 15 minutes.

Transfer the soup to a blender and puree until smooth.

Return the puree to the saucepan, add the half and half and cook until the soup is just heated through. (This is a good time to make the grilled cheese.)

Season the soup with salt and pepper, garnish with croutons, and serve.