In a stainless steel pan, add oil and onions over medium-high heat. Stir them around and let them cook for 5-7 minutes. Lower the heat and let them keep cooking for 35-45 mins. Keep stirring occasionally after every 5 mins-10 mins so they don’t burn and but don’t stir too much as it won’t let them brown. If you find them sticking too much, add balsamic vinegar and using a spatula scrape it all. This will loosen the onions and infuse flavor. If you feel they are cooking to slow, you can increase heat little bit or vice versa but remember to get the real deal caramelized onion takes around 35-50 mins. So have patience!