Using a house hold electronic pressure cooker is a big help with this.
Place loin inside after seasoning fatty side up adding just enough water or broth or beer.
After setting your cooker to meat, and securing the lid, select max time if less than approximately four to five hours.
Wash and peel vegetables cut carrots in 3rd's to produce close to equal size sticks. Either french cut on onion or medium dice works too.
Using prebaked potatoes oiled with rendered bacon fat, slice them in 1/2 " thick discs
Using a sauce pan add carrots and water to cover tops bring to boil and simmer on medium high till tender adding salt and lemon juice.
In a 13" pan with plenty of depth and surface area add oil, butter, and onion.
Once the onions release their moister and start to become slightly translucent add garlic simmer for just a moment.
Add potatoes to onion and garlic as well as season salt let it all brown and carmalize. Cover and reduce heat to simmer on low.
After carrots become tender to your liking strain excess water, return pan to low heat stir in brown sugar and butter. Rest oon low heat and cover.
Check pork loin to make sure that it is finished the bone should come right out with little effort. Allow at least thirty minutes to rest before serving.
Remember to always be safe and sanitary.