Preheat your air fryer to 390°F (200°C) for 3 minutes. This ensures proper cooking temperature right from the start.
Prepare the Brussels sprouts by placing them in a bowl and tossing with 1½ tablespoons olive oil, balsamic vinegar, half the minced garlic, ¼ teaspoon salt, and ¼ teaspoon pepper until evenly coated.
Spread the Brussels sprouts in the air fryer basket in a single layer. Cook for 8 minutes, shaking the basket halfway through, until they begin to brown on the edges.
Meanwhile, prepare the salmon by patting fillets dry with paper towels (this is crucial for crispy skin). In a small bowl, mix remaining olive oil, garlic, lemon zest, lemon juice, dill, smoked paprika, and remaining salt and pepper.
Brush the salmon fillets with the seasoning mixture on all sides, making sure to coat evenly.
Push the Brussels sprouts to the sides of the air fryer basket, creating space in the center. Place the salmon fillets skin-side down in the center.
Reduce temperature to 370°F (185°C) and cook for 7-10 minutes, depending on thickness, until salmon reaches an internal temperature of 145°F or flakes easily with a fork.
Serve immediately with lemon wedges, placing the salmon over a bed of the Brussels sprouts for an attractive presentation.