Start by washing the beets thoroughly under running water to remove any dirt. Once clean, peel the beets using a vegetable peeler. Cut them into quarters to make them easier to cook.
Place the quartered beets in a large pot and cover them with water. Bring the water to a boil, then reduce the heat to a simmer. Cook the beets for about 30-40 minutes or until they are tender when pierced with a fork. Drain the beets and let them cool slightly.
While the beets are cooling, take your fresh horseradish and grate it finely using a grater. Be cautious, as fresh horseradish can be quite pungent, and the aroma may sting your eyes.
In a large mixing bowl, combine the cooked beets, freshly grated horseradish, salt, vinegar, sugar, and mixed spices. Stir the mixture well until all the ingredients are fully incorporated.
Give your Tsvikli (Beet-and-Horseradish Relish) a taste. You may want to adjust the sweetness or spiciness by adding more sugar or horseradish, depending on your preference.
Transfer the relish into clean glass jars, leaving about half an inch of headspace at the top. Seal the jars tightly.
Place the jars in the refrigerator and allow the Tsvikli to chill for at least 24 hours before serving. This resting time allows the flavors to meld beautifully.