Bring a medium sized pan of water to boil, add 1 cup of basil and boil for 15 seconds then drain. Plunge basil into ice water, drain and pat dry. Combine basil and broth in a blender and process until smooth.
Let mixture stand 2 hours at room temperature. Strain through a fine sieve into a bowl and discard solids. Add vinegar and salt, stirring with a whisk.
Salad
Arrange the yellow and red tomato slices alternately in a shallow bowl or on a platter. Drizzle with the basil sauce, sprinkle with the cheese and pepper. Top with the 1/2 cup sliced basil leaves. Serve immediately.