The correct answers are: The soup served in a hollowed-out pumpkin tasted suspiciously like dish soap. The waiter carrying the flaming desserts tripped over the owner's cat.

"served in a hollowed-out pumpkin" correctly reduces a passive relative clause (which was served).

"carrying the flaming desserts" correctly reduces an active relative clause (who was carrying).

The sentence about the chef has two main verbs ("was yelling" and "threw") and needs either a relative pronoun (who was yelling) or a reduction (yelling).

The sentence about the steak uses the active present participle ("ordering") instead of the passive past participle ("ordered").

The sentence about the dessert contains a full relative clause ("which was covered"), not a reduced one.