Korean Air has round-trip flights from Dallas (DFW) to Ho Chi Minh City or Manila (SGN, MNL) for $795-$875 with a connection. Flights in August and October. 7-day minimum stay required.
Some small OTAs on Skyscanner have this for as low as $772; which is cheaper than the airline. If you plan on booking there, beware of any site that charges a fee to cancel a ticket within the 24-hour “free” period. Use unknown booking sites at your own risk.
Manila fares are in August only.