Something watered down compared to the alternative, from the practice of adding boiling water to normally brewed tea to create a drink with less flavor and/or caffeine.
His proposal for reducing the deficit is rather weak tea.
When doing a "job" and the pay is not up to standers that would be seen a profitable
"The last two jobs we've had are weak tea, taking on passengers won't be near enough. We don't get paid for this cargo we don't have enough money to fuel the ship, let alone keep her in repair... she'll be dead in the water" -Malcolm Remolds from Fire Fly episode 1 "Serenity"