Bulgogi

Freeze steak until semi-frozen, at least 2 1/2 hours and up to 5.

Slice steak 1/8" thick against the grain and transfer to a large bowl.

In a food processor, puree chopped onion, garlic, apple, and kiwi until smooth, about 1 minute. Pour over meat, then add sliced onions, scallions, brown sugar, soy sauce, mirin, oil, and 1/4 tsp. pepper.

Using your hands, massage marinade into meat, about 2 minutes. Cover bowl with plastic wrap and refrigerate at least 30 minutes and up to 2 1/2 hours.

Heat a large nonstick skillet over medium-high heat. Working in batches, arrange meat in a single layer without overcrowding. Cook, turning once and using tongs to move meat along sides of skillet if skillet becomes too dark, until meat develops a dark, caramelized crust on both sides, 3 to 4 minutes per side. Continue to cook, flipping and tossing meat so it picks up any caramelization from bottom of skillet, until parts of meat look charred, about 1 minute more. Transfer to a large platter; repeat with remaining meat. If skillet gets too dark, wipe out skillet between batches. Discard excess marinade.

Top bulgogi with scallions and sesame seeds (if using). Serve with rice alongside.