Preheat your oven to 425°F. Line a baking sheet with parchment paper or aluminum foil. Drizzle a little olive oil on the paper and spread it around with your fingers to prevent sticking.
Pat the salmon fillet dry with paper towels on both sides. The surface should look matte, not shiny — this ensures browning, not steaming.
Sprinkle salt and black pepper evenly over all sides of the salmon, including the sides (the fat cap).
In a small bowl, whisk together the Dijon mustard, honey, minced garlic, and lemon juice. Taste — it should be tangy with a hint of sweetness. Adjust honey if needed.
Place the salmon skin-side down (if using skin) on the prepared baking sheet. Spoon the mustard mixture over the top and spread it evenly with the back of a spoon or a pastry brush. There should be no bare spots.
Bake for 10–12 minutes, depending on thickness. For a 1-inch fillet, 11 minutes is about right. The glaze should bubble and caramelize. If using an instant-read thermometer, pull the salmon at 130°F for medium (it will rise to 135°F as it rests). Without a thermometer, gently press the thickest part — it should flake easily but still look moist, not dry.
Remove from the oven and let the salmon rest on the baking sheet for 3–5 minutes. Do not skip this step — the carryover cooking finishes the fish and the juices redistribute for the most tender bite.
Sprinkle with fresh dill and/or parsley, squeeze a lemon wedge over the top, and serve immediately. Leftovers keep in the fridge for up to 3 days — great flaked over salad or reheated gently in a 300°F oven.