In soup pot, cook the onions with olive oil until tender, stirring occasionally.
Add boiling water, salt and pepper. Stir once or twice.
In a large bowl mix the meatball ingredients. (I use the leftover egg white. We'll use the yolk in the sauce.) Make small balls from the mix.
Put flour in a relatively plain, low sided plate and roll each of the meatballs until you cover them thoroughly. (You can use a large plate to put all the meatballs in the flour and shake the plate.) Discard the leftover flour.
Carefully and slowly put the meatballs in boiling water and bring them boil. To not to harm the shapes of the meatballs do not stir much.
Add potato, carrot, celery and peas and bring them boil.
In a small cup beat the yolk and lemon juice.
Check the meatballs and veggies, if they are cooked as you desire turn off the heat. Quickly stirring, pour 1-2 spoon boiling water of the meatballs into yolk-lemon mix. (We warm the yolk this way so it is not going to be cooked when we pour it in the stew.) Pour it into the stew and stir.