For the relish: In a bowl, blend the corn, green onions, yellow onions, vinegar, vegetable juice and some salt and pepper, mixing well. Hold in the refrigerator for 30 minutes to 1 hour to marinate.
For the grits: Warm the chicken stock in a deep saucepan over medium-high heat. Bring stock to a simmer, then add the salt and pepper. Reduce the heat to medium. Next slowly add the grits. Whisking continuously, cook until thickened, 10 to 12 minutes. Once cooked, taste and season with salt and pepper. Then hold warm for serving.
For the sauce: Heat a pan with the grapseed oil. Then add the onions and cook until caramelized, 3 minutes. After cooking the onions, reduce the heat to medium-low and add the apple juice. Allow the juice to reduce for 1 minute, then add the pepper puree. Stir to incorporate the flavors and simmer for 5 minutes, then remove from the heat.
For the fish: Heat a heavy-bottom pan over high heat. Add the grapeseed oil and warm for 2 minutes. Then sprinkle the skin-side of the fish with the blackening seasoning and sear on the skin side for 3 minutes. After "blackening" the skin side, flip, reduce the heat and cook for another 3 minutes on the fleshy side. When fully cooked, scoop 2 ounces of the sauce on a plate followed by some grits. Top with the cooked fish. Finally top a corner of the fish with some relish.