I recently went on one of these walks as I haven't had a chance to explore Southall yet and figured it would be the best way to do it.
Monisha guides you through Southall where you can try different foods & drinks from the street sellers and talks about the community there. You don't just learn about Indian food but about the neighbourhood, their migration to the UK, religion etc. It really was so interesting, and as we were a very small group we could ask her lots of qsts throughout the walk.
You end the walk at Quality Foods (wow, what a great store) and she can help you with explaining the different ingrediants you may want for your curry dishes etc. The produce was fantastic - a huge choice and really fresh.
For anyone who doesn't know Southall it is a great introduction.