Learn Spanish (Latin America): Serviremos la porción como el cliente pida. - We will serve the portion however the customer asks.

In this sentence, como means "however" or "in whatever way." Because we don't yet know how the customer is going to ask for it—it's an unspecific, future request—we use the subjunctive (pida). If we were talking about a specific, known way a customer always asks for it, we would use the indicative (como pide).

Does como always trigger the subjunctive?

No, it depends on whether the action is a known fact or an unknown possibility. If you say Servimos la porción como el cliente pide using the indicative, it means "We serve the portion the way the customer asks" (a known, factual routine). But because this sentence talks about an unknown, future request, como triggers the subjunctive.

Why doesn't the sentence say pida por to mean "asks for"?

The verb pedir already translates to "to request" or "to ask for." The word "for" is built directly into the verb's meaning, so adding por or para after it is a common English-speaker mistake you can simply skip!

Why is there an "i" in pida instead of an "e" like in pedir?

Pedir is an "e-to-i" stem-changing verb. To form the present subjunctive, you always start with the "yo" form of the present indicative, which is yo pido. Then, you drop the "-o" and add the opposite ending for the third-person singular customer, which gives you pida.