Heat some oil in a large pot. Add the diced onion and the sausage. Sauté over medium heat until the sausage starts releasing some fat and the onions turn translucent.
Push the onions and sausage to one side, and let some oil pool in the empty area (add more oil if needed).
Mix the chili powder into the hot oil until it’s fragrant. If you like, add other seasonings here, like cumin or garlic powder. Once the spices are coated in oil, mix them into the onion and sausage.
Add the chopped brisket and stir well to coat the chunks with the chili powder.
Add the barbecue sauce, the can of Ro-Tel, and the ½ can of water (you could also use beer or chicken stock for a more flavorful liquid). Mix well and bring to a simmer.
Cut the crust off the white bread and cube it. Add it to the chili as a thickener (for a gluten-free option, you could crush some Fritos or tortilla chips instead). Mix well.
Let the mixture simmer for 20 minutes or so, and then season to taste with salt and pepper.
For Frito pie, grate cheese and sprinkle atop a layer of Fritos in a bowl. Pour the chili over the top and add more cheese (I prefer two layers of cheese in my Frito pies) and slices of pickled jalapeño. Enjoy.