Tomato Soup with Quinoa and Pesto

In a heavy small nonreactive saucepan, combine the quinoa, 2/3 cup water, and the salt and bring to a boil over high heat. Reduce the heat to low, cover, and simmer for 15 to 20 minutes, or until the water is absorbed and the grains are translucent and begin to uncoil. Set the saucepan aside, covered. Meanwhile, in a food processor fitted with the metal blade, process the tomatoes with their puree until almost smooth. In a heavy large saucepan, heat the oil over medium-high heat. Stir in the onions, garlic, pepper, and sugar and saute for 5 to 6 minutes, or until the onions are tender and light golden. Stir in the pureed tomatoes and broth. Increase the heat to high and bring to a boil. Reduce heat to medium-low and simmer, uncovered, stirring occasionally, for 15 minutes, or until the soup is slightly thickened. Meanwhile, prepare the pesto: In a food processor fitted with the metal blade, combine the basil, Parmesan, oil, broth, sour cream, and garlic and process to a smooth paste. To serve, fluff the quinoa with a fork and stir into the soup. Ladle the soup into warmed bowls and top each serving with about 1 tablespoon of the pesto, swirling it through the soup. Garnish with basil sprigs, if desired.