Rinse the beef and cut it into 1/2-inch cubes. Season with a little salt and black pepper, and let it marinate for about 10 minutes. Lightly coat the beef with cornstarch.

Clean the bell peppers and onion, then cut them into 3/4-inch cubes.

Heat a deep skillet and add a generous amount of vegetable oil. When the oil is hot, add the onion, bell peppers, and garlic (cut the cloves in half) and quickly fry them. Remove and drain on paper towels.

Add the beef to the hot oil and sear over high heat for about 2 minutes (wait until the oil is hot again after adding the beef). Remove and drain.

For the sauce, mix together the oyster sauce, ketchup, simple syrup, water, and black pepper until well combined.

Pour out the excess oil from the skillet. Return the seared vegetables and beef to the pan, add the sauce, and stir-fry everything together for 1 minute. If the pan gets too dry, add a little more water to prevent burning.

Transfer to a plate and serve. Enjoy! 🤤