Season the beef with salt, then toss together.
Sprinkle with tapioca starch then toss until evenly covered.
Heat avocado oil in a skillet over medium high heat.
Working in batches, drop the beef in the oil a few at a time so the pieces aren't touching each other. Fry until dark and crispy, about 1 1/2 minutes on each side.
Remove from the skillet and set aside. Drain the oil from the skillet but leave about 1 tablespoon.
Add garlic, ginger, and crushed red peppers, if using, into the same skillet.
Sauté until fragrant, about 1 minute.
Add coconut aminos, water, and fish sauce, and stir to combine.
Add the fried beef, and let it simmer for 3 minutes until the sauce is thickened.
Stir in green onions and simmer for 2 more minutes.
Remove from heat and stir in sesame oil.
Sprinkle with sesame seeds before serving with cauliflower rice.