Preheat the oven to 375 degrees F (190 degrees C).

Place potatoes in a large pot and cover with lightly salted water; bring to a boil. Cook until tender, about 10 minutes. Drain and let cool.

Wash pork stomach thoroughly in cold water. Stuff stomach until full, alternating with potatoes, sausage, and cabbage, and seasoning with salt and pepper. Try to make even layers, imagining how it will look when you slice it. Fold stomach closed; place in a shallow roasting pan. If you have any leftover stuffing ingredients, place them in the pan around stomach.

Roast, uncovered, in the preheated oven until sausage cooked through and stomach browned and crispy, 40 to 50 minutes. Cut into 2-inch slices; serve piping hot. You can make gravy out of the drippings if desired, but it is good by itself as a whole meal.