Hidden Hanoi do walking tours related to food and cooking classes and are pretty good;- http://www.hiddenhanoi.com.vn/

Thanks i did see that one nd it sounded pretty good. I have been to viet nam a few times but not ha noi. I am planning a culinary and cultural tour to viet nam next february..thanks again!

You may find some more ideas on Rick Steins Far East Oddysey (English TV prog & Book)which was pretty good, Youtube link to part one:
http://www.youtube.com/watch?v=igH_Lunrnv4

I went walking with Hanoi Cooking Centre and was fascinated by the new flavour sensations from the street stalls. The expedition lasted more than four hours and was worth every bite, with the guides eager to talk about how the food was central to their lives. The cooking lab at the school look well-equipped for hands-on experience but I took a class at Hidden Hanoi in a more atmospheric setting. Again the theme was food as culture.
In either case the prices were great value compared to European schools.
http://hanoicookingcentre.com/
It's amusing, by the way, to see how celebrity TV chefs/curmudgeons Gordon Ramsay and Anthony Bourdain are portrayed as having eaten at every bistro in the central part of the city.