Heat a large skillet over medium-high heat for about 1 minute until hot.

Add 1 pound ground beef and break it apart with a wooden spoon; cook 5 to 7 minutes until fully browned, stirring frequently.

Tilt the skillet and drain off excess fat, leaving about 1 tablespoon in the pan.

Add 1 small finely diced onion and cook 2 to 3 minutes until translucent.

Add 2 cloves minced garlic and cook 30 seconds until fragrant.

Pour in 15 ounces tomato sauce, then add 2 tablespoons ketchup, 1 tablespoon brown sugar, 1 tablespoon apple cider vinegar, 1 teaspoon Worcestershire sauce, 1/2 teaspoon smoked paprika, 1/2 teaspoon chili powder, and 1/4 teaspoon cayenne pepper; stir 1 minute to combine.

Increase heat to medium and bring sauce to a gentle simmer, about 1 to 2 minutes.

Reduce heat to medium-low and simmer uncovered for 5 to 7 minutes, stirring occasionally, until sauce thickens.

While sauce simmers, split buns, brush cut sides with butter, and toast under broiler or in toaster oven 1 to 2 minutes until golden.

Taste the meat mixture and adjust salt, sugar, or chili powder as needed.

Assemble sandwiches by spooning meat onto bottom buns, topping with the other halves, and serving immediately.