-
1
Whisk honey, 1/4 cup lemon juice, 2 Tbsp. oil, and 1 tsp. salt in a large bowl. Add kohlrabi, apple, and onion and toss to coat. Let sit while you cook the fish.
-
2
Swirl remaining 1 Tbsp. oil in a large nonstick skillet to coat. Season fish generously on both sides with salt and pepper and place, skin side down, in cold skillet. Set over medium heat and cook until fat starts to cook out of fish, about 4 minutes. Gently press on fillets with a spatula so skin makes good contact with pan, then keep pressing, cycling from one fillet to the next every few seconds, until skin starts to crisp. Continue to cook without pressing until skin is super crisp and flesh is mostly opaque, 8-10 minutes total (adjust heat as needed, but don't rush it). Turn over; cook until completely opaque, about 1 minute. Place skin side up on plates.
-
3
Wipe out skillet and return to medium heat. Cook hazelnuts and butter, swirling pan often, until butter foams, then browns, about 4 minutes. Remove from heat and stir in remaining 2 tsp. lemon juice; season brown butter sauce with salt and pepper.
-
4
Toss kohlrabi salad and serve alongside fish fillets, leaving excess dressing behind. Spoon brown butter sauce over fish and salad and serve with lemon wedges for squeezing over.
