we will need:

2 onions,
1 tablespoon of wheat flour,
1.5 L of water,
50 grams of grated cheese,
Wheat bread for croutons,
80g butter,
Green pepper to taste,
salt to taste
Cooking
At the bottom of the pressure cooker without a lid fry the onion chopped in half rings in butter, sprinkle the onion with flour and stir until the mass starts to brown.
Fill with cold water, close the lid tightly, add salt and pepper and simmer for 10 minutes. When done, release steam in slow decompression mode.
Prepare croutons or white bread toast before serving. Pour the soup into the soup bowls, put hot toast in each bowl and sprinkle with grated cheese.