Set your water bath to 185 degrees for 45 mintues.
Add the frozen veggies to a bag with olive oil, garlic powder, and kosher salt. Seal the bag. If vacuum sealing try to avoid getting oil at the top of the bag, so that it won't interfere with gettig a good seal.
Add to the water bath once it comes to temperature.
If at any point the bag starts to float, weight it down. A small, heavy duty pot works.
When the time is up, remove the bag from the water bath with a pair of tongs.
Remove from the bag and enjoy immediately.
Notes
If you want firmer broccoli and cauliflower, try cooking it for 30 minutes instead of 45.