Steps
1. Pat the mackerel fillet dry and season both sides with salt and pepper.
2. Heat olive oil in a non-stick skillet over medium-high heat.
3. Place the mackerel skin side down and cook for 4-5 minutes until the skin is crispy.
4. Flip and cook the other side for 2-3 minutes until the fish is cooked through.
5. Meanwhile, combine lemon zest, lemon juice, minced garlic, chopped parsley, Dijon mustard, and yogurt (if using) in a small bowl to make the sauce.
6. Remove the mackerel from heat and plate it.
7. Spoon the lemon herb sauce over the mackerel and serve immediately.