Heat a large wok or skillet over medium-high heat. Add 2 tbsp of avocado oil and, in batches to prevent overcrowding the skillet, sear the beef until a golden brown crust begins to form, about 2 minutes a side. Transfer cooked beef to a side plate and continue until all of the beef is browned and set aside. (If your skillet ever runs dry, you can add more oil, as needed).
Add an additional teaspoon of avocado oil (if needed) and the toasted sesame oil. Add the onions, crushed red pepper flakes, ground sichuan peppercorns, cumin and garlic. Toast spices, stirring, until fragrant, 1 to 2 minutes, being careful not to burn.
Add the beef and toss until well coated in the spices. Add the coconut aminos, fish sauce rice vinegar, and green onions. Stir to combine. Cook, stirring, until the sauce has just thickened, 2 to 3 more minutes.