Mince 4 garlic cloves. Place half in a large bowl and reserve for the Brussels sprouts. Place the remaining garlic in a small bowl. Chop 1 teaspoon fresh thyme leaves, and juice 1 lemon, and add to the small bowl. Add 1 tablespoon of the olive oil, 1 teaspoon of the kosher salt, and 1/2 teaspoon of the black pepper, and whisk to combine. Brush all over the salmon fillets.
Preheat an Instant Vortex Plus 7-in-1 Air Fryer Oven to 400ºF and set for 10 minutes. Grease the air fryer racks with cooking spray. Place the salmon fillets skin-side down in the bottom rack of the air fryer, leaving space between the fillets.
Add the remaining 1 tablespoon olive oil, 1 teaspoon kosher salt, and 1/2 teaspoon freshly ground black pepper to the large bowl with garlic, and stir to combine. Trim and halve 1 pound Brussels sprouts, add to the bowl, and toss to combine. Place in the top rack of the air fryer above the salmon. Air fry until the salmon is cooked to desired doneness, 6 to 8 minutes.
Remove the tray of salmon. Continue air frying the Brussels sprouts until golden brown and crispy, 1 to 3 minutes more. Meanwhile, whisk 1 tablespoon balsamic vinegar and 1 tablespoon honey together until combined.
Drizzle the honey vinegar over the finished Brussels sprouts before serving.