Zest the lemon first and add a teaspoon of zest, lemon juice, olive oil, apple cider vinegar, salt and pepper to a bowl. Use a whisk to combine the dressing ingredients.
Slice the cucumber and beets and add to a large bowl. Slice the mozzarella cheese into bite sized pieces and add to the bowl.
Drizzle with the lemon dressing and sprinkle with fresh chopped tarragon. Stir to combine and cover the salad with dressing. Serve chilled or at room temperature.