NGINX - 1 NIC in DMZ and 1 NIC in LAN questions

Hi

I am looking at deploying NGINX as a reverse proxy solution in my environment.I am also new to this (Linux and Nginx).
I have a DMZ and a LAN segment defined in my firewall.
The NGINX box will have 2 NICs:

- NIC1 10.0.0.X (DMZ)
- NIC2 192.168.0.X (LAN)

Internet requests will be NAT-ed to the DMZ IP of the Nginx server, then Nginx will transfer the request to it LAN NIC and finally to the back end server.
Well in theory cause when I tested it didn't work.

I know the firewall and DMZ/LAN segments work as I already have other infrastructure that works without any issues (A Netscaler).

The question that I have (and found incredibility hard to find information on the configuration required) is about the routing from DMZ NIC to LAN NIC on the Nginx server.
How can I make this happen (so I don't have to NAT to the LAN NIC of the Nginx server). If it is a Nginx config can someone post an example?

Or does this needs to happen at OS level? Or is easier to create a bridge?

Thanks