Yes.

1. Go to System Emails (admin/emails).
2. Find the Subscription: Meals To Choose Reminder card, under the Client tab.
3. Click Send Emails.

This works a bit differently from the automatic version: it does not skip subscribers who already got a reminder — it re-emails everyone currently due (anyone with meals still to choose for an upcoming delivery date), even people who already received the automatic reminder. Each subscriber still only gets one email per click, even if they have several delivery dates due. It's a bulk send to everyone currently due, not a way to email one specific person, and there's no confirmation step — clicking it sends right away.

This is the only automated email in System Emails with a manual Send Emails button; every other one is sent automatically only, either on a trigger or on its own schedule.