Place the diced beets, potatoes, kidney beans, pickles, red onion, parsley, olive oil, apple cider vinegar, salt, and black pepper in a large mixing bowl.
3 medium beets, cooked and diced, 2 medium potatoes, cooked and diced, 1 can red kidney beans, drained and rinsed, 4 dill pickles, diced, ¼ medium red onion, finely diced, 3 tbsp olive oil, 1 tbsp apple cider vinegar, ½ tsp salt, or to taste, ¼ tsp black pepper, or to taste, 2 tbsp fresh parsley, finely chopped