Preheat the oven to 400*. Preheat a large skillet over med-high heat. Add 2 T oil and heat until oil begins to shimmer. Sprinkle both sides of fish liberally with salt and pepper. Place fish in hot pan and DO NOT touch it for a couple of minutes. Once it has cooked for 2-3 min, gently nudge one of the steaks and if it releases from the pan, flip the steaks over. If it doesn't move, let them cook a bit longer, checking to see if they release every min or so. They should have a nice crust on the cooked side now.
Once you have flipped the fish, place the pan in the preheated oven and roast for 10-15 minutes depending on the thickness of your steaks.
Meanwhile, combine all the herbs, nuts, lemon juice and zest, garlic, red pepper and a pinch of salt and pepper in a blender or food processor. Pulse to chop up the herbs, then begin to drizzle in the oil until a nice thick sauce consistency is reached. Pour into a dish and stir in the parm if using. Taste for seasoning and add more salt, pepper, or lemon as needed.
Remove fish to a plate, sprinkle with lemon zest and squeeze a bit of lemon juice over each. Top with pesto.
*I serve with green beans, baby carrots, and squash that I steam in the microwave for a few minutes. Then I season them with salt, pepper, and a clove of minced garlic and toss them in with the fish about the last 5 min of roasting. Just don't cover the fish up, or you'll lose the crust on top. push the fish to the side of the pan and put the veggies on the other side. You can top the veggies with some of the leftover pesto. I put both the veggies and the fish on top of "Cauliflower Rice." (Basically just mince some onion and garlic and saute with a bit of olive oil, then add in cauliflower that has been pulsed in the food processor til resembles rice, cook 5 minutes, then season with salt and pepper.).