Place the shallots in boiling water for approx. 1 minute, drain, peel and halve if necessary. Clean the mushrooms. Peel the garlic and cut into thin slices. Choose as large a pan as possible so that the vegetables have enough space. Heat olive oil in it. Fry the vegetables and garlic vigorously in it and season with pepper from the mill and salt. Then deglaze with sherry and vinegar and let simmer covered for 10 minutes so that the vegetables absorb the stock. Put everything in a glass bowl and chill overnight.