OK, from a mid-west Iowa boy of Czech/German family, this is how brats were done every Saturday all summer and fall long.
Dad grabbed a case of beer and threw it into the cooler with ice, Mom snagged out 2-3 bottles.
A cast iron kettle was fired up, Mom grabbed a white tupperware out of the back of the fridge with the lard and scooped out a big spoonful, dropped into the kettle, 2 slivered up onions were tossed in to brown up. Whenever she remembered to come back to the stove the beer was poured in, along with any leftover stock she wanted to use up, or even water to top up to what she thought was sufficient.
A mess of brats were dumped in and simmered at such a low level bubbles hardly broke the surface.
At this point a lot of beer was gone and the grill had a nice coal base slowly dying down.
The brats were pulled out to a plate only to hit the grill. The onions were sieved out and placed in a aluminum pan with a pad of butter, the pan placed off on the side of the grill, someone always splashed a little more beer into the onions.
More beer was placed into the cooler, grilling occured, illicit fireworks often erupted, kids with fresh band aids sensed dinner was ready.
THe deck picnic table was lined with warm kraut, 2-3 varieties of mustard (stone, horseradish, dijon), ketchup, the onions, rarely pickle relish, and then the regular summer picnic sides.
I'm pretty certain this happened roughly 2-3,000 times in my youth.