Might be a job for tasker, the most famous automation tool. Other automation tools might be capable of the same (think about llama) – but as a Tasker user I'll describe it this way (feel free to adapt).
The "task" to be exececuted would be:
- Keyguard › Off
Disable screen lock. Might require the SecureSettings Plugin if the native variant doesn't work.
- Media Control › Pause
to stop your podcast, music, or whatever media stuff might be running. This can be set as "toggle". You might need to experiment a little here; consider e.g. what would happen with "toggle" when no podcast is currently played – that would have the opposite effect then, so maybe better just "pause" here directly.
- Launch App
Select your voice recorder here.
Note that manipulating app controls is more tricky (and might require root). I didn't play with that, so I cannot give advice on it. I just know theoretically that Tasker is capable of that as well. Another tricky thing is the "continue podcast" part, which might not be wanted if it wasn't played before – but you've got the idea, I hope.
Now, we need a trigger and assign it the task from above. Multiple choices here with Tasker alone – and many more with the tons of plugins available (see e.g. my collection of Tasker resources). So I only give an example here which should make sense:
Shake lets you define a shake-pattern. So e.g. "shake the device twice from left-to-right" could trigger above action.
Even limited to the steps I've explicitly described, this would minimize the steps you need to take: Shake the device, hit "record", hit "save", and then (optionally) continue your podcast.