Modifications:
+ Since I was at the dacha, I baked the beets in the coals. It was an interesting experience.
+ The mushrooms were, accordingly, on skewers. They turned out great, much better than frying them in a pan.
- There were no pumpkin seeds. Well, it's a minor issue.
- I only had good olive oil. There was no good vinegar at all, so I did without it. However, it still turned out pretty good, although I wanted to try it as in the recipe.
Overall, I'm very satisfied. As a bonus, I baked a pear in the coals as an experiment. It caramelized! I didn't expect it, but I was pleased.