Combine water, 1 teaspoon cumin, 4 sliced garlic cloves, and chicken in a large saucepan. Cover and bring to a boil over medium-high heat. Reduce heat to medium-low; cook 10 minutes or until chicken is done. Drain, and place chicken on a cutting board. Cut chicken across grain into thin slices; keep warm.
Remove 2 tablespoons adobo sauce from can; set aside. Remove 2 chipotle chiles from can; finely chop and set aside. Reserve remaining chiles and adobo sauce for another use.
Heat oil in a large nonstick skillet over medium-high heat. Add 1 tablespoon minced garlic; sauté 3 minutes or until just beginning to brown. Add 1 teaspoon cumin; sauté 1 minute. Stir in tomato puree; cook 4 minutes or until mixture thickens to a pastelike consistency, stirring constantly. Stir in reserved 2 tablespoons adobo sauce, 2 chopped chipotle chiles, vinegar, honey, Worcestershire, and 1/4 teaspoon salt. Add sliced chicken to sauce; simmer for 3 minutes or until thoroughly heated.
Split rolls in half; arrange in a single layer, cut sides up, on a baking sheet. Broil 1 minute or until lightly toasted. Remove top halves of rolls from baking sheet. Divide chicken mixture evenly among bottom halves of rolls, and top chicken mixture evenly with cheese. Broil chicken-topped rolls 2 minutes or until cheese melts. Remove from oven; top with onion and top roll halves. Serve immediately.