Preheat and prep: Heat your oven to 400°F (200°C). Line a baking sheet with parchment for easy cleanup.
Pat the salmon dry with paper towels.
Make the herb mix: In a small bowl, combine lemon zest, half the lemon juice, parsley, dill, garlic, olive oil, salt, and pepper. If using Dijon or red pepper flakes, stir them in now.
Season the salmon: Place the fillets on the sheet, skin-side down if using skin-on. Spread the herb mixture evenly over the top.
Add a thin lemon slice to each fillet.
Bake: Cook for 9–12 minutes, depending on thickness, until the salmon flakes easily and is just opaque in the center. For thicker fillets, go to 14 minutes, but avoid overcooking.
Finish: Squeeze the remaining lemon juice over the salmon right before serving. Taste and add a pinch more salt if needed.
Optional pan-sear: For crisper edges, sear in a lightly oiled skillet over medium-high for 2–3 minutes per side, then reduce heat to medium and cook 1–2 minutes more.
Optional air fryer: Air fry at 390°F (200°C) for 7–10 minutes, depending on thickness.