Slow-Roasted BBQ Brisket Sliders

Ingredients

• *FOR THE BBQ BRISKET:*
• 4 pounds brisket
• Kosher salt
• Freshly ground black pepper
• 2 cups ketchup
• 1 cup water
• 1/8 cup red wine vinegar
• 2 tablespoons Worcestershire sauce
• 1/2 cup brown sugar
• 2 garlic cloves, grated
• *FOR THE SLIDERS:*
• 3 tablespoons butter, divided
• 2 white onions, super thinly sliced
• 2 tablespoons water
• 1 pinch kosher salt
• 12 slider buns (potato buns are best)
• 8 ounces cheddar, sliced (or shredded)