In large nonstick skillet with a lid, heat oil for a few minutes, then add potatoes. Sprinkle with half of seasoned salt and cook for 5 minutes.
Stir potatoes and season other side with other half of salt. Cook 5 more minutes.
Test potatoes. When they are firm but edible, add onion, green pepper, and mushrooms. Increase heat to medium-high and stir to distribute. Leave potatoes until they begin to take on some color, then turn, repeating until potato cubes have light browning on all sides and are nearly at desired texture for eating.
Scramble eggs and season with pepper. In a separate pan, scramble eggs to runny, half-finished consistency, then distribute over top of potatoes.
Top potatoes and eggs with cheese mixture. Reduce heat to low, put lid on skillet, and leave covered about 5 more minutes, until cheese is melted.