Vegetarian cabbage rolls

I love cabbage rolls, in Russia we call them Golubtsi.
I Always thought that it was a Russian or Ukrainian dish but when I came to Canada I found out that Canadians are familiar with cabbage rolls...The name is different but the ingredients and methods are the same.
Well, I'm going to present a vegetarian version of this dish :-)

Ingredients:
1 cabbage
1/2 cup long rice (cooked)
1 tomato
2 stalks of celery
2 big carrots
1 bell pepper
100 g mushrooms
1 onion
2 cloves of garlic
1 can crushed tomatoes (or tomato paste)
salt, pepper

How to cook:

Mix rice, chopped celery, chopped tomato, chopped bell pepper in a bowl.
Chop carrots and onions, put 2 tbl spoons of olive oil in a pan, put there chopped onion and carrots, fry stirring until it's soft then mix in a bowl with other ingredients. In the same pan put chopped mushrooms, fry for 10 minutes with a dash of salt and pepper, mix with other ingredients in a bowl.
Mince 2 cloves of garlic in the same bowl, add some salt and pepper to taste. Leave the mixture for a bit.
So, Dear Cabbage...rinse it first and undress it very carefully, putting every leaf aside.
Bring to a boil a big pot of water and boil every leaf for 7 minutes, putting it aside to drain and cool after that.
And there we go....we have leafs of cabbage and our beautiful mixture! What we are doing next is...we are putting the mixture on every leaf and folding it like an envelope.
After all our little envelopes are  folded, we put a pan on a stove, we add 3 tbl spoons of olive oil and frying every envelope, so it's golden brown from both sides...then add crushed tomatoes (or tomato paste) to the pan, cover it, reduce heat to low and simmer it for 30-40 minutes.
Voila! It's ready to serve!!!