In a medium saucepan, combine the beef stock, apple cider vinegar, and beer. Bring to a gentle simmer over medium heat.

Add the melted butter and maple syrup, whisking until well combined.

Mix in all the dry seasonings (black pepper, granulated garlic, smoked paprika, cayenne if using, and salt). Continue to simmer for 2-3 minutes, stirring occasionally.

Remove from heat and let cool completely to room temperature, about 45 minutes. Strain through a fine-mesh strainer to remove any particles that might clog the injector.

For injection: Place your brisket on a clean work surface. Using a meat injector, insert the needle at a 45-degree angle every 1.5 inches in a grid pattern across the brisket. Inject slowly until you see the liquid just starting to escape.

Focus extra attention on the thicker parts of the brisket, particularly the point section if you're working with a whole packer brisket.

Pro tip: Make this marinade the day before and refrigerate overnight to let the flavors develop fully. Just bring it to room temperature before injecting.

The maple syrup provides a similar rich sweetness to molasses but adds a more subtle, complex flavor that pairs beautifully with the beef and smoky notes.