Disabling IPv6 on *one* network interface in Debian

[Frank Bulk]

Due to our network setup I have asymmetric traffic occurring (post-IPv4 NAT
result) that can be resolved by disabling IPv6 on one of the server's VLANs.
I removed the IPv6 addresses manually using "ip -6 addr del <IPv address>
dev eth0.<VLAN number>" but that will only last until the next reboot.

Any ideas on how to disable IPv6 on *one* network interface in Debian?  My
google fu has failed me.

Frank