In a large skillet, heat the oil, one turn of the pan, over medium-high. Add the beef and cook, stirring and breaking up with a spoon, until browned and finely crumbled, about 4 minutes; season with salt and pepper. Add the chili powder, celery seed and cumin; stir until the spices are toasted, about 1 minute. Add the onion and garlic and cook, stirring often, until softened, 2 to 3 minutes longer. Add the brown sugar, tomato paste and 1 tbsp. mustard; stir until combined. Add the stock and 3/4 cup water and let simmer, stirring occasionally, until thickened, about 15 minutes.
In a large saucepan, cover the hot dogs with water; bring to a simmer and cook until heated through, about 5 minutes. (Or, if you like your dogs with extra snappy casings, heat a griddle pan over medium-high and grill the hot dogs, turning, until heated through, about 5 minutes.)
Place the dogs in rolls. Top with chili sauce, a zigzag of mustard and some chopped onions.