The appositive phrase in the sentence "His favorite meal, chicken and dumplings, is bubbling on the stove," is "chicken and dumplings."
An appositive is a noun or noun phrase that renames another noun right beside it. The appositive can be a short or long combination of words.
It is fundamental to know that appositive is always separated from the rest of the sentence with commas, as in the sentence provided.
In the example, the appositive "chicken and dumplings" renames the noun meal (favorite meal).