Differences between bulky vs compact AC Step Up & Step Down solutions for high power loads?
This may or may not be an answer! Ideally you could find a dual voltage cooker. All that is required by the manufacturer is to have two 110 V elements with a series (220 V) or parallel (110 V) switching arrangement. This avoids the transformer issue completely.







simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. Dual voltage switch arrangement.

If there happen to be two elements in your cooker you could do this yourself but waterproofing would be an issue. Take care.