Finely chop the onion, ginger, garlic, and lemongrass. In a bowl, mix the ground beef with the ginger, garlic, lemongrass, and 2 tablespoons oyster sauce. Stir well, add 1 tablespoon cooking oil, mix again, and let marinate for 15 minutes.

Wash the wild betel leaves and finely chop or mince them.

Heat a skillet over high heat (using a non-nonstick pan will help the beef brown better). Add 2 tablespoons cooking oil and sauté the chopped onion until fragrant. Add the marinated ground beef and stir quickly over high heat.

When the beef is just cooked through, add the chopped wild betel leaves and stir until the leaves are wilted and the beef is fully cooked. Sprinkle with a little black pepper or chili to taste, if desired.

Serve hot with shrimp chips or rice crackers.