Cooking baby potatoes and small carrots with it. It is only about 2 pounds. Hoo Honestly never cooked a pork roast beforeand there are so many different ways I am really confused.
The purpose of covering anything is to retain moisture as steam in the pan, instead of letting it evaporate away. So, using a pan that has a tight cover allows you to control the amount of moisture in the resulting cooked food.
Because you're cooking vegetables along with your pork roast, being able to cover the pan for at least part of the cooking time, can be helpful because it will allow the vegetables to steam, so they won't get dried out.
If you leave the cover on for the entire period, you'll steam the meat — it will cook, but it won't be as appealing. Start out with the oven preheated to a high temperature (at least 450F or so), and with just the roast in the pan, uncovered, just until the outside begins to brown. For a small or medium roast, this should be no more than about 15 to 25 minutes, and you may wish to turn the roast once or twice during this period.
Now add your vegetables, cover the pan, and turn the oven down to a slow temperature (285-315F). In addition to your potatoes and carrots, you may wish to add some chopped onion, celery, and/or green pepper. Those vegetables will release lots of moisture (especially if you add salt), and along with the meat, create a nice broth so your other vegetables won't dry out.
Cooked slowly along with the vegetables, the roast will be very tender and flavorful. It may take an hour or more, depending of course, on the size and shape of the roast. A meat thermometer is the best way to determine when the roast is cooked. For pork, the coolest temperature in the center should be 170F (77C), but take it out a couple degrees lower because it will still cook a bit after coming out of the oven.
There are lots of different ways to treat a roast. However the basics are the same even if the techniques are different.
You want to sear the outside of the roast, or at least the top of it if not the whole thing. You can do this by putting the roast under the broiler (500F) for 20 minutes. This will create a nice crispy top.
After that you can load in your veg. Carrots and potatoes can go in at the same time, as can turnips. Parsnips I would put in about an hour before serving, and anything softer I would put in about 30 minutes prior to serving.
So do you want that crispy top or do you want the flavor of it in the "soup" that develops? If you want it crispy, leave it uncovered by the veg, but then also make sure there is enough moisture to cover the veg so they don't burn. I like to use wine as the principle moisture in roasts and stews, but many people like beer, and others just broth of some sort.
If you don't care how crispy the top is, then feel free to load up on veg, and put the cover on. Make sure you leave enough room between the top of the veg/water and the lid otherwise as the mass expands with the simmering/boiling it will over run the top of the pot/Dutch oven or whatever. Leave room to add more veg if you are adding softer veg later on.
Follow the recipe you have if you haven't done a few already, and you'll be just fine.
I make a nice marinade with soy and fruit juice and beer or wine. Make it kinda thick so it clings to the meat. Put some in the bottom of the the pan with water. Garlic, salt, and pepper rubbed in or just sprinkled on the roast. Broil open for 15 minutes or so and then cover and low temp for a couple hours. Works great with rice.
The other way is cover the thing with green salsa and keep it covered with water in the pan and cook long and slow at 300+/- Works great for tacos and burritos. Use the resulting gravy to ladle over the burritos. Sprinkle cheese and BOOM!