Cook rice according to package directions, omitting salt and fat.
Combine sour cream and 1 tablespoon salsa, stirring well. Set aside.
Combine brown rice, 2/3 cup salsa, green onion, and next 3 ingredients in a large bowl, stirring gently. Arrange 1 cup lettuce on each of 4 individual salad plates. Spoon rice mixture evenly onto lettuce. Sprinkle evenly with cheese. Top evenly with sour cream mixture.