In a skillet cook the bacon until it is crisp and transfer it to paper towels to drain. In the fat remaining in the skillet cook the leek, covered, over moderately low heat, stirring occasionally, for 10 minutes, or until it is softened, and stir in the tomato, the tarragon, the half-and-half, the broth, and salt and pepper to taste. Bring the liquid to a boil,cook the mixture over moderate heat, stirring occasionally, for 5 minutes, or until it is thickened, and stir in the bacon.
