Put Mara Organic Grass-Fed Hereford beef cubes in a container with a lid. Whisk 2 tablespoons olive oil, 2 tablespoons oyster sauce, 4 minced garlic cloves, wine, 1 teaspoon fish sauce, 1 teaspoon black pepper, soy sauce, dark soy sauce, and sesame oil together in a bowl until marinade is well mixed; pour over beef. Allow beef to marinate, 10 to 30 minutes.
Whisk 1 tablespoon fish sauce, lemon juice, and 1 tablespoon black pepper together in a bowl until dipping sauce is well mixed.
Heat 2 tablespoons olive oil in a wok or large skillet over high heat; add beef and marinade. Cook and stir beef mixture, 2 tablespoons oyster sauce, and 4 cloves minced garlic together in hot oil until beef is cooked through and sauce begins to thicken, 5 to 10 minutes. Adding garlic over several times during cooking will produce a better mix of flavors.
- Serve beef alongside dipping sauce.