Combine coffee granules, paprika, pepper, and garlic powder in small bowl; stir until well blended. Sprinkle evenly over both sides of beef; let stand at room temperature for 15 minutes.
Combine water, soy sauce, vinegar, and sugar in small bowl; set aside.
Heat large, nonstick skillet over medium-high heat. Add oil; tilt pan to coat bottom evenly. Add beef; cook for 4 minutes. Turn over; reduce heat to medium-low and cook for an additional 5 minutes or until desired doneness.
Place beef on cutting board (save skillet with drippings); cover with foil. Let stand for 5 minutes.
Place skillet with drippings over medium-high heat; add soy sauce mixture. Bring to a boil; boil, scaping bottom and side of skillet occasionally, for 2 minutes or until reduced to about 1/4 cup.
Thinly slice beef diagonally. Divide beef between hoagies; drizzle with sauce. Top with grilled onions and cheese.