According to available sources, the consumption of a dish that might be called “hrenovina” (for example, cold mushrooms with horseradish) complies with the rules of Orthodox fasting.

Mushrooms with Horseradish: A Tradition in Orthodox Fasting

According to available sources, the consumption of a dish that might be called “hrenovina” (for example, cold mushrooms with horseradish) complies with the rules of Orthodox fasting. The description provided in the source " link txt" states that the menu for the Lenten meal, even in the most sophisticated restaurants during Great Lent, included mushroom dishes – including “cold mushrooms with horseradish.” This indicates that such a dish did not violate the prescribed fasting restrictions (such as the prohibition on meat, fish, or dairy products).

Therefore, when it comes to the preparation and consumption of a mushroom-based dish with horseradish, it fully conforms to the principles of fasting nutrition, as its composition meets the requirements of the Lenten table.

Supporting citation(s):
"During fasts, in all restaurants, taverns, even the finest establishments on Nevsky Prospect, the choice of dishes was no different from what was eaten in monasteries. ... cold mushrooms with horseradish, ..." (source: link txt)