• Sprinkle seasoning on one or both sides of the fish. Go as heavy or light as you like. 
• Grill fish on a George Foreman or other indoor grill for about 5-6 minutes.
• Stir relish and mayo together to make tartar sauce.
• Serve fish on buns with tartar sauce. Add lettuce, tomato and red onion if desired.

Homemade mayonnaise:

• Combine egg yolk, lemon juice, vinegar, mustard, and ½ tsp. salt in a medium bowl.
• Whisk until blended and bright yellow, about 30 seconds.
• Using ¼ tsp. measure and whisking constantly, add ¼ cup oil to the yolk mixture, a few drops at a time, for about 4 minutes.
• Gradually add the remaining ½ cup oil in a very slow thin stream, whisking constantly, until mayonnaise is thick, about 8 minutes - mayonnaise will be lighter in color.
• Cover and chill. Can be made up to 2 days ahead and chilled until ready to use.