In medium saucepan over medium-high heat, reduce watermelon juice to 2/3 cup. Toward end of reduction, add garlic. Remove from heat, cool 10 minutes then add soy sauce, brown sugar, hot sauce and bourbon. Mix well.

Place watermelon-bourbon glaze in large zip-top bag. Add steak and massage to cover meat. Close bag and refrigerate 3-4 hours.

Heat grill to high heat. Remove steak from plastic bag and gently shake to remove excess glaze.

Grill steak 4-6 minutes; turn, grill 4-6 minutes, depending on thickness of steak. Remove from heat. Steak should be pink in center.

Allow steak to rest on platter or cutting board 10 minutes.

Mix small amount of watermelon-bourbon glaze with cornstarch. In small saucepan over medium-high heat, add cornstarch mixture to remaining glaze and simmer 3-5 minutes. Reduce to medium heat until mixture thickens. Remove from heat.

Cut flank steak on bias into thin strips. Drizzle watermelon-bourbon glaze over top.