Red Onion Relish:
Place onions in a pot, and cover. Cook on low heat for 15 minutes, stirring occasionally until onions are translucent. Add lemon juice, cover and simmer on medium heat for 5 minutes. Add sugar and red wine vinegar, and continue to cook 4 more minutes, until mixture is thick and onions have cooked through.
Gorgonzola Grits:
In another pot, bring chicken broth, water and half-and-half to a boil over medium-high heat. Gradually whisk in grits. Reduce heat to medium-low, and cover. Cook 5 to 7 minutes or until thickened, stirring occasionally. Add remaining grits, stirring until well blended. Remove from heat, and allow to cool slightly.
Seared Catfish:
Lightly drizzle the fillets with olive oil, and then season with salt and pepper.
Add seasoned fillets, presentation side down, to a very hot cast-iron skillet, and sear for 2 to 3 minutes to get a nice crust. Carefully turn and sear other side, about 3 minutes. Remove from heat, and set aside.
Serve over grits, and top with onion relish.