Another intuitive, no-math (and I believe best) strategy could be as follows:
The prisoner that gets steak the first night should always vote 2 (Don't know). The other two prisoners that get fish tacos the first night should vote 1 until they get steak for the first time, then vote 1 (Steaks) every night from then on.
This ensures that
- The majority won't vote 1 (Steaks) when they would be wrong.
- The majority will vote 1 the first night they all had steak.