I'm a big fan of Mexican food. Not the Fake-Mex stuff they sell at Chiquito's ("Have you ever eaten a fajeeta before?") but authentic Mexican cooking. Unfortunately, it's pretty difficult to track down Mexican ingredients in London, as UK supermarkets stock a narrow range of Tex-Mex focussed products.
You can get the basic fresh ingredients from most supermarkets, including coriander and chillis. If you look in the specialist food sections of Sainsburys and Tesco you can find a limited range of Mexican ingredients including dried chillis and masa harina (a corn based flour used to make tortillas, tamales and other Mexican dishes such as gorditas).There's the 'World Foods' aisle where you can grab Tex-Mex ingredients including pickled jalapenos and habaneros.
However, for a wider range you need to buy from one of the very few shops that sell authentic Mexican ingredients in the UK.
Mexican Ingredient Specialists in London
Here are some companies that specialise in Mexican ingredients in the London area: El Burrito, Casa Mexico and The Cool Chile Company.
Inside the El Burrito restaurant in Charlotte Street, there is a small area that sells essential Mexican ingredients. Check out some photos of the Mexican ingredients for sale at El Burrito on their Flickr page.
Casa Mexico has a shop in Winkley Street, East London that sells a wide range of Mexican goods, including tinned and dried ingredients. You can also buy Mexican ingredients online from Casa Mexico - just watch out for the delivery costs if you're buying lots of tinned ingredients.
I use Casa Mexico a lot. I've bought many ingredients including dried Mexican chillis, tinned Tomatillos and Mexican oregano. One of my favourite ingredients is tinned salsa chipotle, a smokey, fruity sauce that I use in my pork chilli.
I've also bought some Mexican utensils from Case Mexico, including a molcajete y tejalote pestle and mortar that, once seasoned, is excellent for making authentic salsas.
The Cool Chile Co
The Cool Chile Company has been supplying dried chillies, masa harina and some other Mexican ingredients to the major supermarkets. It was only while researching this article that I realised they have 2 shops - one in Westbourne Grove, London and the other at Borough Market. You can also buy Mexican ingredients online from The Cool Chile Company.
Update (21st Feb 2010) : I visited the Cool Chile Co in Westbourne grove. It's actually a shelfing unit inside the Taqueria restaurant. There isn't a a massive range of ingredients on sale but I did buy some ancho chilli powder, pasilla chilli powder, corn tortillas and a tin of nopales.
Buy authentic Mexican ingredients online
I don't know of any specialist shops selling Mexican ingredients outside of the London area - if you know of any, please let me know by commenting to this article.
In the meantime, the best bet is to buy online from one of the retailers listed below: