Answer: Although I enjoy chocolate ice cream
Explanation: An adverbial clause is a group of words that together function as an adverb. In this sentence, the adverbial clause is an adverb of concession with the subordinating conjunction "Although", and it is the one that contrasts the main idea. The sentence "Although I enjoy chocolate ice cream" explains that their favorite flavor is strawberry, despite them liking chocolate ice-cream, having then the function that an adverb would have by itself. Moreover, an adverbial clause contains a subject and a verb; In this case, "enjoy" is the verb and "chocolate ice-cream the subject.