In order to poach bratwurst in beer, you will need to assemble your ingredients and have everything on hand before you start. You will need:  Bratwurst: use as many as will fit into your pan or as many as you plan to serve One medium-sized white, yellow or sweet onion 6 ounces of dark beer Use 1 medium-sized white, yellow or sweet onion. Chop the onion into rings.  These will cook with the bratwurst, giving a nice flavor and companion to the sausage. Use either a heavy skillet or a Dutch oven to cook the brats and onions. Turn the burner on a medium high heat. Melt about 1 tablespoon of butter and make sure the butter covers the entire bottom of the pan. Brown the onions in the butter for 1-2 minutes. Stir them frequently to make sure they are browned on all sides. Some recipes suggest cooking the onions after you cook the bratwurst, so that you can monitor the bratwurst more effectively and so that you don’t risk overcooking the onions. Cook the bratwurst with the onion for 2 minutes. Then turn over the bratwurst using tongs and let them cook for another 2 minutes. Both sides should be nicely browned. Slowly pour 6 ounces of dark beer (about half a regular sized bottle) into the pan. Cover the pan with a lid. Turn down the burner’s heat to medium to medium-low. Allow this to cook with the bratwurst and onions for approximately 15 minutes. The beer will poach the bratwurst, adding good flavor to the sausage. Remove the brats from the pan using a pair of tongs, and put them on a plate. Transfer them to a pre-heated grill. Let them cook for 5-7 minutes, turning them over at least once halfway through the cooking time. Take the brats off the grill with tongs and place them on a serving plate. Dish up the onions on the same plate. Alternately, you can use a casserole dish or the Dutch oven to serve the bratwurst.

TL;DR in Vietnamese:
Chuẩn bị nguyên liệu. Cắt hành tây. Đun chảy bơ trong chảo có đáy nặng. Cho hành tây vào. Cho xúc xích Bratwurst vào chảo. Đổ bia vào chảo. Hoàn tất quá trình chế biến trên vỉ nướng. Gắp xúc xích khỏi vỉ nướng.