Kevin Roecker never liked the idea of pouring out the pot after cooking brats in beer.
So the Peoria chef came up with Chef Kevin’s Brat Sauce, which can be used as a condiment served warm.

CHEF KEVIN’S BRAT SAUCE
2 tablespoons butter
1 large onion (about 2½ cups) sliced
1 teaspoon dry thyme leaves
1 teaspoon pepper
1 bay leaf
½ teaspoon salt
24 ounces beer (the darker the beer, the richer the sauce flavor will be; Roecker likes Samuel Adams Boston Lager)
24 ounces water
10 to 12 bratwurst
4 tablespoons brown or stone ground mustard
2 tablespoons ketchup
1 teaspoon paprika
1 teaspoon brown sugar
2 tablespoons pickle relish (sweet or dill)

In a stock pot or Dutch oven, melt the butter over medium high heat. Add onions and brown lightly. Stir in salt, thyme, pepper and bay leaf. Add beer and water. Bring this mixture to a boil for five minutes.

Reduce heat to medium. Add bratwurst. Simmer (never allow to boil) for 20 minutes.
Remove brats and let them rest at room temperature for 20 minutes, then refrigerate until ready to grill.

After removing the brats, add mustard, ketchup, paprika and brown sugar to brat-simmering liquid.

Over high heat, reduce mixture to mustard consistency. Be very careful when mixture starts to get thick as it can burn. 

Turn down heat to medium-low when mixture gets thick and stir frequently. Add pickle relish and cook another 10 minutes. Remove bay leaf and serve or keep warm.