Add the pepper, onion, thyme, basil, parsley, and rosemary in a blender. Blend till slightly coarse.
Pour the blended mix into a pan or saucepan and add all the remaining ingredients and oil. Using a spoon, stir to combine.
Simmer on medium heat for about 4 minutes until some water evaporates and the oil floats. Set aside to be cooling.
Meanwhile, spread aluminum foil on a baking sheet and place the fish on it. Make deep diagonal slits on both sides of the fish using a knife.
Using a brush, apply the cooked marinade on both sides and in the belly and head of the fish, making sure it goes deep into the slits. You can save some of the marinade as a dip.
Put the lemon slices inside the belly of the fish and wrap the fish with aluminum foil.
Grill or broil in a preheated oven for 30 minutes 400℉.
Remove from the oven and open the foil, be careful because the steam might burn.
Serve with the saved cooked marinade with a choice of sides. ENJOY!