Preheat your oven to 375°F (190°C).
Prepare a baking dish by lightly greasing it with olive oil.
In a small bowl, mix together the Dijon mustard, honey, olive oil, dried thyme, salt, and pepper.
Place the salmon fillets in the prepared baking dish, skin-side down.
Spread the mustard mixture evenly over the top of each salmon fillet.
Bake in the preheated oven for 15-20 minutes, or until the salmon flakes easily with a fork.
Remove from the oven and let rest for a few minutes before serving.
Garnish with lemon slices before serving.