This is another question to which we will answer that, in theory, you can reheat rings in the microwave, but you really shouldn't. Like other dishes for which crunchiness is the biggest trump card, onion rings are simply not intended to be heated in the microwave. We know it's the fastest way to reheat anything literally, but a microwave will no doubt ruin the crunchiness of your delicious onion rings, and they'll become yucky.