In a medium bowl, combine tuna, celery, relish, mayonnaise and lemon juice and mix well.
Spray small frying pan with non-stick cooking spray. Heat over medium low heat. Place tortilla in pan. Place 1/2 tuna mixture on one half of each tortilla and top with 1/4 cup cheddar cheese and top with second tortilla.
Cook for 1 - 2 minutes until tortilla begins to brown; flip tortilla and cook on second side until browned and cheese begins to bubble (approximately 1 - 2 minutes).
Remove from pan and cut into wedges and serve.