Boil potatoes until done.
Cool and cut into bite size pieces and put in a large bowl.
In a skillet sauté onions, green peppers and celery until tender.
Add garlic and cook about 1 minute or until fragrant.
Add the sour cream, sautéed vegetables, and pimentos to potatoes until mixed together.
Add a little more sour cream if the mixture is too dry.
Fold in 1 to 1 ½ of the cheddar cheese.
Put mixture in a buttered 9 x11 casserole dish and top with the remaining cheese.
Bake at 350° for about 30 minutes or until heated all the way through.
Let set for 5 minutes then serve.
Chef's notes: Can make a day ahead store in refrigerator. Next day let set on counter for 20-30 minutes before baking. May take a little longer to bake. Original recipe credited to Fran Millender Hoover.