Try doing malt extract agar. Super simple recipe
20g agar agar powder
18g Light Malt Extract
850ml water
1g nutritional yeast
Mix agar powder with LME and yeast. Heat up 850ml water on stove until hot (not boiling), add powder and stir whilst bubbling for 15 minutes. Pour into glass bottle/jar and wrap lid with foil (add a hole to the lid with polyfil to allow pressure buildup to be released) and put into pressure cooker with water level with the agar level in bottle. pressure cook for 30-45m at 15psi. After, leave the PC off to decompress for about 20mins. Take out of PC and place into your SAB - leave to cool for a further 20-35mins (this is the hardest part - you want it to be cool enough to handle but not too cool that it starts solidifying).
Have your dishes lined up in their bags in your SAB also. Wipe everything down with 70% ISO.
Stack dishes 10 dishes high (or 5 high on a little platform to make it easier to pour) right side up (lid on top). To pour, pour from the bottom up so start with the bottom plate and lift all other plates with the lid. Pour and then place down the lid and move up the stack. After all have been poured, leave for 12-24 hours then you can use to inoculate or wrap for future use.
I have a ton of mushroom cultivation info in my thread. I currently do rye grain agar which is the same recipe, but without the yeast and LME. literally just powder and water from boiling the rye grain.