Heat oil in a large/deep pot over medium-high and saute onions and garlic until tender. Add potatoes, cook 5 minutes.
Add 8 ounces of beer, drink remaining 4 ounces. Add a few grinds of salt and pepper. Bring to a boil while cutting kielbasa.
Slice sausage into fourths lengthwise, then cut into bite-size pieces. Add to potatoes. Reduce heat to medium, cover and cook 10 minutes, stirring once midway through.
Test potatoes for doneness. Cooking time may take up to 5 minutes more. If your liquid is mostly evaporated, do this cooking with the lid on. If your mixture has too much liquid, cook uncovered to allow excess moisture to evaporate.
Serve sprinkled with cilantro and cheese. Top with condiments of your choosing. We like ranch or sour cream and hot sauce.
Makes 4 reasonable portions. If you have a big appetite, serves 2.