Take another look at the sentence:
Francis ate his burger alone at the cafeteria table, which he ordered with
no onions and extra pickle.
Which he ordered with no onions and extra pickle, an adjective clause, comes right after table, an illogical target. Burgers, not tables, get flavored with condiments! Before you continue, review the rules for misplaced and dangling modifiers.
Go back to the sentence to try again.