* Tzatziki sauce can be found at grocery store deli counters.
Preheat conventional oven to 425°F. Lightly grease baking pan. Place char, skin side down, in pan and brush lightly with olive oil and sprinkle with Greek seasoning. Roast for 16 to 18 minutes or until fish tests done. While fish is roasting make Greek pesto by combining all ingredients in a food processor or blender. Cover and process pesto until almost smooth. Add additional oil, if necessary. Season to taste.
To assemble each sandwich, heat Naan bread on lightly greased grill until warm, but still pliable. Spread tzatziki sauce on top side of the Naan bread then layer lettuce, tomato and onion on one side of top. Slice roasted char into 1/2-inch pieces; layer on top of vegetables. Spoon one Tbsp. of Greek pesto on top of char. Fold Naan bread in half over fish and hold together with a toothpick.