First, create a reminders list called "Evernote" in your iOS Reminders app. Then tell Siri, "Add Evernote reminder [your note here]". This will create a new reminder in your Evernote list, which in turn will append the dictated message to a note in Evernote called "Siri Notes". The future is now!

This Trigger fires every time a new reminder is added to the list you specify.

This Action will append to a note as determined by its title and notebook. Once a note’s size reaches 2MB a new note will be created.

Speak notes to Evernote using Siri and iOS Reminders