Note: Time estimates may vary depending on the size of your roast. Monitor accordingly.

Season chuck roast with salt/pepper to taste.

Heat a skillet over high heat and add half of the butter.

Once butter has melted, add the chuck roast and cook for about 4 minutes on each side until nicely browned, adding the remaining butter to the pan while flipping.

Lower the heat and deglaze the pan with the balsamic vinegar for about a minute.

Optional: If using a slow cooker or instant pot, transfer the meat and vinegar over.

Add in the water and onion; mix.

Cover and cook for the appropriate time or until roast is done. SKILLET (low heat): 2-3 hrs; SLOW COOKER (low): 7-9 hrs; SLOW COOKER (high): 4-5 hours; INSTANT POT: 35 min.

If using skillet or instant pot, remove meat, increase temperature and cook onions uncovered for about 10 minutes to thicken.

Serve meat with onion sauce.