Fire Roasted Tomato Soup

My mom has a tradition of surprising us with little red items on Valentine's Day. Several years ago, our treat was a large can of organic fire-roasted tomatoes with a recipe for tomato soup attached. It's the recipe I have followed ever since.  

Fire Roasted Tomato Soup
1 Tbsp. butter or olive oil
1 medium onion, chopped
2 cloves garlic, minced
2 cans (14.5 oz) fire roasted diced tomatoes, undrained (or, this summer, I've substituted fresh garden tomatoes)
1 can (14 oz) chicken or vegetable broth
2 Tbsp. chopped fresh basil leaves
1 tsp. sugar
1/4 tsp. crushed red pepper flakes
1/2 cup whipping cream or whole milk

In a saucepan, melt butter over medium heat. Add onion and garlic; cook 2 to 3 minutes, stirring constantly, until onion is crisp-tender. Stir in tomatoes, broth, 1 tablespoon of the basil, the sugar and pepper flakes. Heat to boiling. Reduce heat; cover and simmer 15 minutes. Remove from heat; blend until pureed. Stir in cream and remaining 1 tablespoon basil.