Roughly dice the onions and thinly slice the potatoes. Put the oil in a large pan and immediately add the onions. Fry the onions in it for about 6 minutes at high temperature until translucent. After about 4 minutes add the sugar and toss the onions in it. After the entire roasting time of approx. 6 minutes, add the bacon and fry for another 3 minutes. Put the onion and bacon vegetables in a sieve and catch the fat.
Put the potatoes in the same pan and pour the fat over them. Salt and pepper are added so that the potatoes gain flavor and lose the water. Fry the potatoes for about 30 - 40 minutes, swirling them several times (do not put in with a spatula!). When the potatoes are nice and brown and crispy, add the onions and bacon and fry everything again briefly.