Set multi-purpose cooker to brown/sear (or heat large saute pan on medium high heat).
Trim larger chunks of fat off pot roast. If you end up with two or three separate chunks of pot roast that’s fine. Season with seasoned salt and pepper on both sides.
Add canola oil to the multi-purpose cooker pot (or saute pan). Heat oil for 30 seconds then add pot roast. Do NOT touch the pot roast for about 10 minutes while it sears! This is key to developing that beefy flavor for your gravy.
While the pot roast is searing, peel and cut the onion into chunks. I like to cut off the ends of the onion, cut it in half so it can rest flat on the cutting board, then cut each half into 8 chunks.
Wash and cut the red potatoes into halves then cut each half into four equal pieces. If you have some smaller potatoes, cut them so they are about the same size and cut pieces from the larger potatoes.
Wash, peel, and cut the carrots into about 1 ½-inch pieces. Cut the thicker top end of the carrots into half lengthwise.
After 10 minutes of searing the pot roast, flip with tongs and sear the other side for another 10 minutes. Again, do not touch the pot roast while searing!
Clean and cut your mushrooms. If using maitake, just trim off the bottom where the stems connect. If using cremini or button mushrooms, slice or cut into quarters; your preference.
Optional: If you have patience, sear the sides of the pot roast for a couple minutes on each side by leaning it up on the side of the pot/pan.
Remove the meat and place on a plate. Add mushrooms to the pot/pan. Saute mushrooms for 2 to 3 minutes so it soaks up all the fond at the bottom of pot/pan.
Add onions, potatoes, and carrots. Stir and cook for 1 minutes to coat the vegetables with the seasoning from the pot roast and mushrooms.
Push the vegetables to the sides and place the pot roast at the bottom of the pot. If using a saute pan, put the pot roast in the slow cooker then add the vegetables around and on top of the pot roast.
Add 2 cups of water to multi-purpose cooker or slow cooker until the pot roast and vegetables. It's okay if the food sticks out a little over the water because the meat will shrink. Secure the lid and cook on low heat for 6 hours or high heat for 3 hours.
Open the lid and remove the pot roast and vegetables. Optional: If you want to thicken your gravy, set multi-purpose cooker to boil and cook for 5 to 10 minutes. You can also do this on the stove in a pot if you used a slow cooker.
Serve by itself or with a starchy side like steamed rice or bread. Enjoy!