Heat grill pan over medium-high heat or heat outdoor grill. Heat oven to 300F.
Combine tomatoes, jalapeo or Serrano peppers, onions, cilantro, salt and 1 teaspoon of lime zest and the juice of 1 lime.
Coat corn and fish with liberal drizzle of vegetable oil to keep it from sticking to grill. Season the corn and fish with salt and pepper. Season the fish with Old Bay. Cook corn 12-15 minutes until kernels begin to darken in spots. Remove corn and cool to handle, then scrape corn from the cob. Grill fish 8-10 minutes until cooked through and firm. Place fish in bowl and flake the flesh with a fork.
Heat a drizzle of vegetable oil in nonstick skillet over medium heat and add tortilla. Warm tortilla then flip over and sprinkle with shredded cheese, scatter some fish, corn and salsa on half the tortilla and fold over. Cook the taco a minute or 2 on each side to melt the cheese. Keep tacos warm in oven on cooling rack placed over baking sheet until ready to serve. Serve 3 fish tacos per person with Green Rice alongside.