Place cheese and drained pimentos into a food processor with 1/4 cup mayo and pulse just a few times until just mixed.
Check to see if mixture holds together. If it is too dry add more mayo, 1-2 T and pulse once or twice. Check and add additional mayo until you get the consistency you want.
I use just enough mayonnaise to bind, you want to taste the cheese, not the mayo! Do not overmix! Makes about 2 1/2 cups. Keep in refrigerator for up to 1 month.