Re: steamed vs. raw
Hi Bling,
I would say that stir-frying is acceptable if you can't eat those veg' raw.
Some cooking methods apparently have certain nutritional advantages. The anticarcinogenic carotenoid lycopene found in tomatoes becomes more bioavailable when heated in cooking or for canning. A warm cup of broth or bowl of soup is also beneficial to a chilled or tired body for example.
So I would say that it is best to use methods of cooking that minimize nutrient loss and which should maintain the natural state of each food as much as possible; steaming comes out tops.
I would personally only use those fats in stir-frying that remain stable at temperatures above the boiling point: these are butter, olive oil, macadamia nut oil, and unrefined palm and coconut oil. Can't think of any others for the moment.
Definitely avoid using polyunsaturated vegetable oils, including safflower, sunflower, and flax seed oils, as they break down quickly when exposed to air and light, causing harmful substances, such as trans fatty acids, which are linked to many health problems.
However, organic-raw is always best, as no nutrient losses occur at all, unless the veg' are shredded which then exposes them to oxidation, and therefore a corresponding loss of nutrition over time.
Regards
Chrisb1