Building a secure password reset flow using Courier and Next.js 13 requires setting up several services and configuration. A new Next.js web application is created, with Courier configured to handle SMS and email notifications. The app uses Vercel KV for token storage and routes token notifications based on user preferences. Client-side pages are built for creating a user, sending a password reset token, and verifying the token. Server-side routes process form submissions for creating a new user, sending a password reset token, and updating the user's password. Middleware is used to secure routes with authentication checks. The app uses Courier templates for SMS and email notifications, storing user profile and preference data in Courier and using Vercel KV for token storage.