Griddled onions: slice onions into rings and then cut each ring into halves and then quarters. 

Preheat a griddle or a large cast iron skillet on your gas grill or stovetop for 10 minutes. Once the griddle/pan is hot add a tablespoon of oil and toss on the sliced onion. Sprinkle the onion pieces with a pinch of salt and pepper and stir to combine.

Cook the onions for 10 minutes, stirring often.

Split your sausage right down the middle but don't cut all the way through. Open the sausage up and place the sausage directly on the pan or griddle while you continue to cook the onions. 

Grill the sausage for around 15 minutes flipping every 5 minutes or so to try to get some color on the inside and the outside of the sausage. Continue to cook and stir the onions the whole time. If the onions start to look like they are turning dark brown add a teaspoon or two of water and toss them around. 

After the sausage has cooked for at least 15 minutes and the onions start to turn brown and soften, remove both to a plate or cutting board to start sandwich assembly. 

Sandwich assembly: toast your hot dog or brat bun. Add the hot, cooked sausage link and top with a spread of spicy brown mustard.

Pile onions on top of the mustard-covered sausage. Top with a few slices of jalapeno and a drizzle of sriracha on top of the sandwich. 

Serve and enjoy.