Combine the cheese, mayonnaise and onions in a bowl. Stir until well combined. Add the pimentos and hot sauce. Season with salt and pepper. Serve with crackers and celery sticks.
Making ahead: The prepared cheese filling can be refrigerated in an airtight container for up to 2 weeks.
t's tempting to use pre-grated cheese, but pre-grated cheese sometimes contains additives that prevent clumping. It's better to freshly grate your own so the pimento cheese will be creamy--and additive free.