For around two hours, marinate beef in 1 tablespoon oil and 1/2 teaspoon black pepper.

In the meantime, prepare the stir-fry sauce by combining the rice wine, white vinegar, sugar, soy, and fish sauce. Mix just until the sugar dissolves. Place aside.

Separate the meat and the onions into two equal parts. In a wok or big sauté pan, heat 1/4 cup of oil over high heat. (Avoid packing the pan too full to prevent uneven browning of the meat. Depending on the size of your pan and the power of your cooking range, you might need to cook in batches)

Add the first batch of meat in a single layer as soon as the oil starts to smoke. Once a crust has formed, flip it over and brown the other side. It should take 3 to 4 minutes to brown

Stir in the garlic, scallions, and red onion to the pan. For around 30 seconds, shake or swirl the ingredients in the pan

Add stir-fry sauce, stir or shake the ingredients once more.

Add the butter, and simmer while shaking the pan until the butter melts. Get rid of the heat. After cleaning your pan, start the subsequent batch of food.

In a ramekin, combine salt and pepper to make the lime dipping sauce. Over the salt and pepper mixture, drizzle lime juice

Spoon lime dipping sauce over the beef and top with watercress