Rocket stove blasts off My sun oven stays hanging on the wall on overcast days, of which there are many in a Hamilton summer. Even on bright hot days my shabby old model is not efficient enough to bake or roast- its more of a slow cooker specialising in leftovers, rice and stewed fruit. For the pleasure of cooking outside and in the interests of minimising my dependence on the electricity grid I've been wondering what kind of outdoor cooker to bring into my new place. Barbeques are ugly and…