Mix soy sauce, oyster sauce, sugar, sesame oil, 1 tablespoon cornstarch, and ½ cup water. Set aside.
Slice the beef thinly against the grain. Mix with some of the sauce, baking soda, and 1 tablespoon cornstarch. Let sit for 15 minutes.
Cut the ampalaya in half, remove the seeds, and slice thin. Salt, let sit, then rinse and squeeze dry.
Heat oil over high heat. Sear the beef in a single layer, then set aside.
Lower heat to medium. Sauté ginger, garlic, and onion until soft.
Add the ampalaya and cook to your liking.
Turn the heat back up. Add the beef and sauce, then toss until coated and slightly thickened.
Taste, add pepper if you like. Turn off the heat.