Whisk honey, soy sauce, ketchup, garlic, oil, rice vinegar, and pepper in a bowl. Reserve 2 tbsp for glaze.
Toss thighs with remaining marinade and let sit 15–30 minutes if time allows.
Make quick pickled onions: heat vinegar, sugar, salt until dissolved, pour over sliced onion, cool 10 minutes.
Pan-sear thighs over medium-high heat 5–6 minutes per side until internal temp 165°F; brush with reserved glaze in last minute.
Rest 5 minutes, slice thinly. Warm tortillas, fill with chicken, pickled onion, cabbage, cilantro, and a squeeze of lime.