Start the Remix development asset server and the Express server by running:
npm run dev
This starts your app in development mode, which will purge the server require cache when Remix rebuilds assets so you don't need a process manager restarting the express server.
First, build your app for production:
npm run build
Then run the app in production mode:
npm start
Now you'll need to pick a host to deploy it to.
If you're familiar with deploying express applications you should be right at home just make sure to deploy the output of remix build
build/
public/build/