In a medium skillet place chicken breasts, chicken broth or water, bay leaf, and cumin. Bring to boiling; reduce heat. Simmer, covered, for 15 to 20 minutes or until chicken is tender and no longer pink. Drain, reserving broth. Let chicken stand until cool. Use a fork to pull chicken apart into long, thin shreds. Set aside. Remove bay leaf from broth.
Stack tortillas and wrap tightly in foil. Heat in a 350 degree F oven for 10 minutes to soften.
Meanwhile, in a large skillet cook the chopped onion in hot oil until tender but not brown. Carefully add beans; jalapeno, serrano, or green chilies; and 1/4 cup of the reserved broth. With a wooden spoon or potato masher, mash beans in skillet (mixture should be thick). Remove from heat.
Spread 2 to 3 tablespoons of the bean mixture down the middle of each tortilla. Top each with some of the shredded chicken, chayote or orange, cheese, and cilantro or parsley. Fold the sides of each tortilla over the filling, overlapping the sides and forming a cone shape. Fasten each burrito with a wooden toothpick.
Arrange the burritos on a baking sheet. Cover lightly with foil. Bake in a 350 degree F oven for 15 to 20 minutes or until the burritos are heated through. If desired, serve with salsa and garnish with cherry tomatoes and thyme sprigs. Makes 4 to 6 servings.