In "Culture Shock," the Krusty Krab appears to have a salad bar. In this particular episode, Mr. Krabs makes the salad bar free after having a very long loss of customers.
In "Bossy Boots," SpongeBob is ordered to make two salads. Pearl makes one by removing everything from two Krabby Patties except the tomato and lettuce. This shocks SpongeBob, who has apparently never seen a salad before. Even though he is brokenhearted after destroying a couple of Krabby Patties, he sadly brings them to the customers (to the point of tears). They appear to be sad too.