Peel the onions and cut into slices approx. 0.5 cm wide. Sear them in the oil until they turn golden brown. Add cane sugar, salt and pepper. The sugar dissolves quite quickly. Add balsamic vinegar and reduce heat, stirring occasionally. The balsamic vinegar needs enough time to boil down and give off the flavor to the onions, the consistency should be thick, honey-like. So allow enough time, it`s worth it.