Quick Pickled Mushrooms a la Venezuela

My dad being the gourmand he is, sent me a recipe for pickled mushrooms ready to eat in 4 hours. There was nothing super spectacular about the recipe, in Russian, other then the way it was written and described, so I decided to satisfy his curiosity (before he got a chance to make his own). I am not sure exactly if this is a true Venezuelan recipe, however I retained it's name.

1 package of fresh, mixed mushrooms (the original recipe called for button mushrooms)
1/2 cup vegetable oil
1/2 cup of 50% diluted white vinegar
1 tsp walnut oil (my variant)
1 tsp salt
2 tsp sugar
15 green peppercorns (recipe called for black ones and allspice, but this was what I did)
4 cloves of garlic, minced
2 bay leaves

Mix all ingredients in a pan, and bring to a boil. Turn down the heat to medium, and let cook for 4-6 minutes, covered. At this point there will be about double the liquid in the pan, water released from the mushrooms.

Remove from heat, let cool and once at room temperature transfer to the fridge. They are ready to eat after about 4 hours (but I have to admit to trying them sooner).