In a bowl, whisk together the olive oil, soy sauce, lemon juice, Dijon mustard, brown sugar or honey, garlic, paprika, onion powder, pepper, and salt.
Place the chicken thighs in a zip-top bag or shallow dish and pour the marinade over top. Coat well, cover, and refrigerate for at least 1 hour.
Preheat the grill to medium-high heat, about 375°F to 400°F.
Remove the chicken from the marinade and let the excess drip off.
Grill for 5 to 7 minutes per side, or until the thickest part reaches 165°F.
Let rest for 5 minutes before serving.