Place very Sirloin Steak (1.5 pound) on a few layers of paper towels to dry.
Grate half of the Onion (1) for the sauce. Slice the other half of the onion. Slice the handful of Mushroom (1) Mince the Garlic (2 clove).
An optional step here is to add Sea Kelp Stock (1/2 cup) to give extra flavor by simmering 1 cup of water with a piece of dried sea kelp for 10 minutes.
In a small mixing bowl, combine Low-Sodium Soy Sauce (5 tablespoon) Granulated Sugar (3 tablespoon) minced garlic cloves (2), grated onion, and Rice Wine (1 tablespoon).
Also add the Canned Crushed Pineapple (2 tablespoon), Sesame Oil (1 tablespoon), Coarse Black Pepper (1 teaspoon), and sea kelp stock.
Mix well to combine and make your sauce.
Place the beef in a large mixing bowl, pour the sauce, and mix well with your hand. Let it sit for 15 minutes for the meat to soak up the flavor.
With your leftover pineapple, I recommend wrapping them with plastic wrap and freezing them. Then just break off the desired amount for your next cooking needs.
Heat a skillet over the medium-high heat, add some of the beef (you may need to cook 2-3 batches to cook it evenly), onion, and mushroom.
Start tossing all together to cook evenly, about 2-3 minutes
Serve over freshly cooked hot rice and sprinkle Toasted White Sesame Seeds (1 teaspoon). Kimchi would make a wonderful side dish.