French beans, broad beans, peas, Brussels sprouts, etc., will be nice when boiled in preserve jar with a lump of butter, salt, and dash of pepper (and mint to peas), but Brussels sprouts requiring lots of cooking may add some water to it. Spinach and sorrel can be cooked in a jar with a small onion (sliced), and little more salt to sorrel. Any vegetables might be done as above. I think it is an economical way of cooking vegetables; but I am afraid it wouldn't do for large establishments as hotels, etc., but for family houses it is a better way. The jar to be placed in a large pan, half full of water, and see it occasionally to prevent drying up.