Prepare the grill for direct cooking over medium heat (350° to 450°F).
Cut each tomato slice in half to make half-moons. Cut a few well-spaced diagonal shallow slashes crosswise along one side of each hot dog.
Brush the cooking grates clean. Grill the hot dogs over direct medium heat, with the lid closed, until lightly marked on the outside and hot all the way to the center, 4 to 5 minutes, turning occasionally. Remove from the grill.
Brush the cooking grates clean. Grill the hot dogs over medium heat, with the lid closed, until lightly marked on the outside and hot all the way to the center, 4 to 5 minutes, turning occasionally. Remove from the grill.
Place a hot dog in each bun and add two tomato half-moons, two sport peppers, one pickle spear, some onion, and a spoonful of relish. Add mustard and finish with a pinch of celery salt. Serve warm.
