With your charcoal or gas grill create a medium-high heat, your direct cooking zone on half the grill and opposite from that zone have a low to no heat area of the grill, your indirect zone.
In a large pot over high heat open and pour in the beer, then add the onions, brown sugar and butter. Stir until pot starts to simmer. Place bratwurst in the pot and then bring to a boil. Place lid on hot pot and boil for a minute, remove pot from direct heat, leaving covered with the lid on. Allow pot to cool covered for 30 minutes and up to an hour. Drain liquid, being sure to reserve onions and 1/4 cup of cooking liquid. Add the sauerkraut to the onions and stir to mix. Reserve warm.
Place Smoker Bricx ™ directly along the top of the hot coals. Allow the Smoker Bricx ™ to catch a slight fire before closing grill lid. Use grill vents to control the air flow (oxygen) and then you will begin producing consistent smoke.
Grill Bratwurst over direct heat at first being sure to not overly cook, rotating and keeping lid closed as much as possible. Then move grilled bratwurst to indirect zone for 5 to 10 minutes with lid closed on grill down to create more smoke. Remove smoked bratwurst and place directly in warm roll. Top with brown mustard and kraut mix.