Cut the peppers into small cubes, the ham into thin slices, and finely chop the onion and mix it all together.
Break the eggs into the Ziploc ® bag and season with salt and pepper. Close the bag and shake vigorously! Open the bag and add the onion, peppers, ham and grated cheese. Close the bag and shake again to mix all the ingredients together.
Immerse the bag in the pan of simmering water, and cook for 15 minutes. Remove the omelette from the bag and enjoy with tomato sauce and avocado on the side.