Begin by boiling the brats in whatever liquid you're using. I used vegetable broth, because it was what I had on hand.
Saute the onions in the olive oil until the onions are golden brown.
Add the diced potatoes and cover. Add salt and pepper to taste, as well as sage. You will need to stir them occasionally so the onions don't burn. Cook for about 5-10 minutes or until the potatoes are brown and crispy on the edges and flaky on the inside.
Add eggs and mustard, mix, and heat through.
Brown brats in the same skillet and garnish the potatoes with paprika.