... at least heatless for the house!
Obviously, solar drying is a great way to preserve food without using a stove. I find it works great for greens, herbs, flowers and zucchini slices. It works wonderfully to finish off granola when you've toasted all the ingredients separately in a stir-fry pan. I've done melba toast and pita "crackers" in it too.
Steeping liquors and vinegars requires no heat too. Easy recipe: put the fruit in the jar. Add sugar and vodka for a liquor (layering the sugar with the fruit, then covering with vodka. Add vinegar for a fruit vinegar. I made black raspberry vinegar and a tarragon-based (with a few auxillary herbs) vinegar and I use both in salad dressing.
Last year and this I made a lightly salted green vegetable stock. Either put through a food grinder or food processor: 1 part leek, 1 part celery, 1 part parsley (which can be varied a bit with a little bit of thyme and oregano). Salt just so you can taste the salt and pack in jars. This stores nicely in a cool dark place.
When the Sunday before my trip way turned into a hot, humid day and I was faced with nine cucumbers, I knew it was time to try lacto-fermentation. I sliced the cucumbers very thin (about 1/8 of inch or less), sprinkled them lightly with salt and layered them in canning jars. They're down in the cellar and I won't know how they'll come out for a few weeks.
I had a basket of ripe peaches as well. I skinned them, sliced them, layered them in jars with some sugar and filled the jars with brandy. Once a week I'll have to shake them to get the sugar dissolved. Over the winter I should have some yummy brandied peaches and a peach brandy liquor.
For next summer, I'm going to be sure I have some gallon jars on hand to use as "crocks" for lacto-fermented beans as well as cucumbers. With a crock you can layer the stuff in as you harvest it. Talk about convenience!