Sol nad zlato - The Salt Prince (1983)

Rich king Pravoslav has no heir, just three daughters, so he invites all noble suitors to a tournament and lest each princess plead her case for a winner groom. The ambitious elder two and their princes promise gold and military prowess, but the king's favorite, last-born Maruska, chose the gentle son of the magical subterranean salt realm. Their promise of peace and prosperity is despised, her pledge to love father like life-bringing salt deemed an insult, for which she is banned to the forest. The vexed salt prince curses the land so all salt turns into gold, rendering everyone unhappy and unhealthy in a warlike climate. Even with magical help, it takes years -with the king sulking indecisive- till Maruska can undo the curse and gain the throne with the salt prince.