Heat oil to high then sauté (stir-fry) the diced onion until glassy / translucent look, about 3 - 5 minutes.
Add finely diced or crushed garlic then sauté until it gets fragrant, about 1 - 3 minutes.
Add ground beef and sauté until no pink is visible and it is completely browned, about 5 - 10 minutes.
Throw in the chopped Italian pepper, mustard, tomato paste, tomato sauce, water, paprika, salt, black pepper and any optional hot sauce or spices.
Mix well, put the lid on then bring it to boil.
Lower the heat to medium low then let it simmer until about ¼ of the liquid evaporates and the sauce thickens, about 30 minutes. Placing the lid halfway on may speed up the reduction process but the longer we cook the beef, the better taste it will have. Cooking true Bolognese Sauce for 4 hours is not a coincidence. Let the sauce cool somewhat then it's ready t0 be filled into rolls.