8 SERVINGS- The flat cut of brisket holds its shape better than the fattier point cut, and slices more neatly.

1  4-lb piece flat-cut beef brisket, untrimmed

Kosher salt

1/4 cup Dijon mustard

1/4 cup (packed) dark brown sugar

1 tbsp grated peeled ginger

2 tbsp bacon fat or vegetable oil

2 medium onions, thinly sliced

1/4 cup all-purpose flour

1 bay leaf

1  750 ml bottle Belgian-style tripel ale

4  cups beef stock or low sodium chicken broth

Season brisket with salt. Wrap tightly in plastic and chill at least 8 hours.

Let brisket sit at room temperature 1 hour.

Preheat oven to 400*. Mix mustard, brown sugar, and ginger in a small bowl. Unwrap brisket, Place on a wire rack set inside a rimmed baking sheet, and rub mustard mixture all over brisket. Roast until top is nicely browned,30-40 minutes. Remove brisket from oven and reduce oven temperture to 300*.

Meanwhile, heat bacon fat in a large heavy ovenproof pot over medium. Add onions; season with salt and cook, stirring often, until deep golden brown, 8-to 10 minutes. Reduce heat to medium-low, add flour, and cook , stirring often, until mixture smells nutty, about 4 minutes. Add bay leaf,  ale, and stock. Bring to a simmer. Add brisket, cover, and transfer to oven. Braise, turning every 30 minutes, until fork-tender. 3-4 hours. Discard bay leaf.

Transfer brisket to a cutting board and let rest at least 20 minutes.

If braising liquid is thin, bring to a boil, reduce, and simmer, skimming surface as needed, until it coats a spoon; season with salt, if needed. Slice brisket against the grain. Serve with braising liquid.

DO AHEAD: Brisket can be braised 2 days ahead. Cover and chill in braising liquid.