How to Make Caramelized Onions

0 Add the butter to a heavy-bottomed pot over low heat, and once melted, add the sliced onions and sea salt. Stir to combine, place a lid on top, and let the onions wilt for 30 minutes.
1 After 30 minutes, take the lid off of the skillet and toss the onions in the butter. Turn the heat up to medium-low, and let the onions continue to caramelize, uncovered, for 45 minutes, scraping the pan and stirring the onions occasionally. 
2 Use the caramelized onions right away or store them in an airtight jar or container in the fridge for up to a week.