FOR THE AIOLI:
Add mustard, lemon juice and zest, garlic, salt and pepper to ½ cup good quality mayonnaise. Using a fork, blend well. Note, if you want to make homemade aioli, see instructions in the note section.
FOR THE LING COD
Preheat oven to 400 degrees.
Heat a large, preferably non-stick, skillet over medium high heat. Once the skillet is hot, add 1 tablespoon olive oil. Season fish generously with salt and pepper. When the oil is hot and shimmering, add fillets and cook about 2 minutes until golden brown and crisp. Gently turn fish and cook another 2 minutes.
Place the ling cod fillets on a sheet pan that's been oiled, sprayed with non-stick cooking spray and covered in parchment paper. Roast fillets for about 10 minutes, or until done. To tell if the fillets are done, press the back of the fillets and if the fish shows a hint of separating or flaking the fillets are ready.
FOR THE GREENS:
In the meantime Adjust heat to medium, and add 3 tablespoons olive oil to the same skillet. Quickly sauté garlic and red pepper flakes, approximately 30 seconds, until fragrant. Add greens to the pan and season with salt and pepper. Use tongs to move the chard around the pan to wilt evenly. Add lemon juice just before serving.