Gather all the necessary ingredients. You'll need bratwurst sausages, onions (sliced), pretzel dough (prepared or store-bought), beer (your choice of brew), butter, salt, and any additional condiments you prefer, such as mustard or cheese sauce.
Marinate the bratwurst sausages in beer for at least 30 minutes to impart flavor and tenderize the meat. You can also add sliced onions to the marinade for extra flavor.
If you're making your own pretzel dough, follow your chosen recipe. Alternatively, if you're using store-bought dough, let it come to room temperature if it was refrigerated.
Divide the pretzel dough into portions and shape them into traditional pretzel shapes. You can roll out each portion into a long rope and form it into a pretzel shape or experiment with other shapes if you prefer.
Bring a large pot of water to a boil and add baking soda. Boil each pretzel for about 30 seconds, then remove and place them on a baking sheet lined with parchment paper.
Preheat your grill to medium-high heat. Remove the bratwurst sausages from the beer marinade and grill them along with the sliced onions until they are cooked through and have grill marks, typically about 10-15 minutes, turning occasionally.
Preheat your oven according to the instructions for your pretzel dough. Bake the pretzels until they are golden brown and cooked through, typically about 12-15 minutes.
Once everything is cooked, assemble your meal. Place grilled bratwurst sausages on the pretzel buns, top with grilled onions, and serve with your favorite condiments. Enjoy your delicious Grilled Bratwurst with Onions and Beer Pretzels!