Place beef in freezer to firm up enough to slice very thinly (about 1/4”). Blend remaining ingredients except for salt, sesame seeds, black pepper, and kochukaru until smooth. Add beef to marinade stirring gently to make sure all is coated and marinate about 7 hours.
Heat oven to 200º F. Drain beef, blot dry with paper towels and place on a rack on top of a baking sheet. Grind the salt and sesame seeds in a mortar and pestle (you can use a spice grinder, just be sure not to turn the mixture into a paste). Sprinkle over beef, then grind fresh black pepper and add chili if desired.
Bake about four hours, rotating pans halfway through, until dried and jerky-like. Store in a sealed container in the fridge.
