Chop beef cheeks into 2-3 large chunks each. Place in your slow cooker (oven instructions below) with the soy sauce, 5-spice, most of the green onions, chillies and 1/2 cup water.
Cover and cook on low for 10-12 hours or high for 5-6 hours. They’re done when the beef is super tender.
Taste and season with extra soy, if needed (it usually doesn’t). Serve on a bed of rice / cauli rice with with extra green onion on top.