Sous vide

I want a temperature-controlled water tank for food preparation, including things like sous-vide cooking. In particular, it would be very valuable to me to be able to do the following:

1. Cook eggs in the shell without risk of overcooking them, boiling away all the water, exploding the eggs.

2. Heat water for mate to the appropriate mate temperature and maintain it there, rather than boiling water and then mixing it with an unknown amount of water.

3. Controlling the temperature of yogurt so that variations between different batches of yogurt, and different jars in the same batch, are not due to variations in the temperature curve. This way I can experiment with different temperature curves. It would be nice if, as a bonus, I can make larger batches of yogurt.

4. Cook plastic-wrap-wrapped vegetarian sausages at a known temperature without risk of burning the plastic (e.g., when steaming them in a pot there is the risk that the plastic comes in contact with the pot, which is at a higher temperature than the water, or that the water all boils away).

5. Rapidly defrost hermetically-sealed frozen food with a rapid flow of warm water.

There are also fun tricks like cooking part of an egg, or normal sous-vide cooking of meat for long periods of time at low temperatures, but I think of these as much less valuable.

I think this device needs one or more thermometers, a heating element (maybe one of the cheap immersion heaters they sell at truck stops), a relay (or SSR) to control the heating element, a microcontroller, and some kind of water-circulating pump that can handle water at temperature. And, of course, a microcontroller with a well-tuned thermal control system to prevent overshoot.

This is somewhat related to my desire for a dehydrator (see files Notes on circuitry for the Nutra seed activator and Home dehumidifier) for food preparation and food waste handling, the main difference being the heat transport medium — water in the case of the sous-vide cooker, air in the case of the dehydrator. The dehydrator would also probably need to measure humidity.