Dry the mahi mahi fillets and season with salt and pepper.
Melt one Tablespoon of butter and one Tablespoon of oil in a skillet over medium heat.
Add the fillets and cook until golden, about 4 to 5 minutes per side depending on thickness. Transfer the cooked fillets to a plate.
Add the remaining one Tablespoon of oil to the skillet. Add the zucchini noodles and cook for about 2 minutes, or to your desired doneness.
Season with salt and pepper then transfer to a bowl.
Add the remaining two Tablespoons of butter to the skillet. Once melted, add the garlic and pepper flakes/cayenne and cook for one minute.
Stir in the lemon juice, lemon zest and parsley.
Remove from heat and set aside.
Place the zucchini noodles on two dinner plates and top with a mahi fillet. Pour the lemon garlic sauce over the fillets, garnish with additional parsley and serve.
Notes
You can substitute asparagus for the zucchini noodles if you prefer. Cook for 2 to 4 minutes until tender.
I used cayenne pepper but red pepper flakes would also work. Adjust according to your own tastes.