Mix garlic, ginger, tamari and sesame oil in a bowl. Place beef strips in the bowl and cover (can leave for up to 1/2 hour or just while you're prepping the veg)
Heat coconut oil in a wok/large saucepan and add beef when very hot. Cook strips for 3 minutes each side, then take out and place on a plate.
Add vegetables to wok and cook for 5 minutes, then add back the beef.