Rinse the dill and dry with a paper towel. Rinse the eggs as well. Peel the onions. Grate the cheese on a coarse grater. For the omelet, you can use either boiled or raw chicken, only in this case you will need to fry it.
Cut half an onion into half rings.
Cut the boiled chicken fillet into strips.
Break the eggs into a deep bowl.
Add flour and milk to the eggs. Whisk the mixture until smooth and fluffy. Salt and pepper the egg mixture.
Add chopped dill to the egg mixture.
Heat a frying pan and fry the onion in vegetable oil for 4-5 minutes until golden brown. Add chicken.
Pour the egg mixture into the pan and cover it with a lid. Cook the omelette over low heat for 5 minutes.
When the omelette is almost ready, sprinkle it with grated cheese and leave it covered for another 2 minutes until it is ready and the cheese melts. Remove the omelet from the heat.
Add mushrooms or spinach to the omelet. Garnish the dish with fresh spinach leaves. You can also add pesto sauce and sun-dried tomatoes to the omelet.