I'm surprised no one has mentioned using canned wort yet. It eliminates a ton of the risks and challenges of boiling in your flask.
- Difficulty of funneling DME into a flask containing hot water (sticks to the mouth, clumps, etc.)
- Risk of volcano when achieving boil, when adding stir bar, adding yeast nutrient, etc.
- Risk of cracking/breaking the flask while heating
- Risk of cracking/breaking the flask while shock-cooling
- Time spent waiting for wort to boil, then waiting for it to cool
Why not just can starter wort? Then when you need to make a starter, just swirl some StarSan in your flask and dump in the wort. No stressing your flask, no risk of boil-overs, no waiting for things to heat up and cool down.
Isn't the process of canning labor intensive? Does one need a large pressure cooker or is boiling water good enough for wort?
Occasionally I save or prepare starter wort and freeze it. They're typically at 1.072, double starter gravity to save space. I still feel I need to re-boil them before use though.