Special equipment: a 1-quart, resealable, boil-proof (FDA-approved) bag
Bring a large pot of water to a boil, then reduce to a simmer.
Meanwhile, crack the eggs into a 1-quart, resealable, boil-proof (FDA-approved) bag, then seal and smush the eggs to scramble them. Add the cheese, pepper, tomato, onion, ham, mushrooms, salt and pepper, then shake everything together. Squeeze the excess air out of the bag and seal.
Put the bag in the water and simmer until the mixture is set, about 15 minutes; use tongs to remove the bag from the water. Open the bag, roll out the omelet onto a plate and garnish with the chives.