Hearty, savory, warm, filling, and very, very, juicy. I highly recommend serving these in bowls instead of on plates!
In a 6-quart slow cooker, combine the tomato sauce, oregano and pepper.
Wash peppers and pat dry.
If they do not sit upright, slice a very thin piece off the bottom. Finely chop the pieces and place in large bowl.
Add the onion, potato, parsley and crushed red pepper to the bowl, and toss to combine.
Add the sausage and mix to incorporate.
Using a paring knife at a slight angle, cut the tops off the peppers; discard the seeds.
Spoon the sausage mixture (about 1 cup each) into the peppers.
Arrange the peppers upright in the slow cooker and place the tops over the filling. Cover and cook until the sausage is cooked through and the peppers are tender, 5-6 hours on low or 3-4 hours on high.
Using two large spoons, transfer the peppers to serving dish, letting any excess liquid drain into the sauce first. Stir the sauce and serve with peppers.