Alternative to pickling beetroots

The host is planning a dinner and is struggling to finalize the last component of their appetizer. They are making a version of French Laundry's parmesan cups filled with cream cheese, but using Norwegian hard cheese and truffle risotto instead. The combination is expected to be rich and heavy, so they want to balance it out with something sweet and acidic. To achieve this, they considered adding thinly sliced yellow and pink/white beetroots. The beetroots should be softly crunchy, acidic, and retain their vibrant colors. The host initially thought of pickling the beetroots but is concerned it might affect their color and texture. They are seeking advice and tips on how to prepare the beetroots to achieve the desired effect. The goal is to create a visually appealing and balanced appetizer. The host wants to ensure the beetroots are edible and complement the rich flavors of the cheese and risotto. They are open to suggestions and experiences from others who may have tackled a similar challenge.