So here is how I do mine.
Step 1: Sear Your Roast
Once the pan gets very hot, add the pork roast. You want to get every single side nicely browned, for that beautiful flavor. Use a pair of tongs, or two strong forks to help you roll it around. Depending the shape of your roast, you will probably need to hold it in place on some sides.
Once a side is done it should no longer stick to the pan.
(In hindsight I probably should have salted and peppered the pork before searing, in which case I would cut back on those spices in the third step. But I thought mine still turned out fine.)
Step 2: Add Aromatics and Vegetables
Adding things like onions and garlic will help flavor the pork roast while cooking.
Adding veggies makes it a rounded meal. Cooking them with the pork allows them to pick up some amazing flavor. Any hearty vegetable will probably do well. Potatoes are classic, as well as carrots. I've used sweet potatoes in the past too. Turnips, parsnips, celery, etc. could all be added. Consider it a: whatever you have in your fridge, type of thing. If you don't have a potato or some sort of starchy add, pork roast would pair with many starches, like a tomato sauced pasta, or maybe even polenta. It ruins the one pan idea, but it will still taste amazing.
Step 3: Add Flavor
Some of those flavors will get into the vegetables too.
Step 4: Roast
Use a meat thermometer to see if it is done. It should be 160 degrees Fahrenheit on the inside.
Step 5: Rest
While this is happening, I like making a thin sauce, what I would call an au jus. I do this by adding about a cup of chicken stock to the roasting pan, and putting it back on the stovetop. (I actually used chicken bullion dissolved in water, which is why mine looks a little weird) A dash of red wine wouldn't hurt either. Bring this to a simmer. Make sure to scrape the bottom of the pan to get all the stuck on meat flavor in the sauce.
And yes, I leave my veggies in there. They help add flavor. Also, they can look a little dried out when coming out of the oven, so it gives them a glaze and makes them look good. Whether it would still work with potatoes in the pan or not, I'm not sure.
Step 6: Serve
Slice into nice thick slices. You can either move the veggies to the plate, or move the roast back to the pan, it doesn't matter. I think family style service is the best way to go though, all on one platter.
After you dish up your portion you can take some of the sauce and spoon it over your meat.
I hope you try making your own roasts at home. Enjoy!