DIAGNOSIS Silicone is porous and absorbs odors, especially from strong spices, oils, and burnt food. The smell transfers to the steam and flavors your next meal.
FIX The most effective method is to simmer the ring alone in a pot of water with a tablespoon or two of baking soda for 10-15 minutes. Let it cool in the water, then wash with dish soap and air dry completely. For stubborn smells, some people use a vinegar-water soak, but baking soda is better for odor neutralization.
IF THAT DIDN'T WORK Honestly, silicone rings are cheap consumables. If the smell persists after cleaning and it's affecting your food, just replace it. It's good practice to have a spare ring anyway, and you can even dedicate one to savory foods and one to sweet/mild foods if you're particular.
HEADS UP Never put the silicone ring in the dishwasher on a heated dry cycle, as the intense heat can set odors and degrade the rubber faster. Air drying is key. Also, a heavily degraded or cracked ring won't seal properly, so replacement is a safety issue, not just a smell one.