In Britain, we think of chillies as hot, but in Mexico they are as varied and complex as wine. Stevie and Emma head to Oaxaca, Mexico, where chillies go back thousands of years and every local is an aficionado. In the vast Abastos market they discover some of the region's 150 different varieties. Whether fresh or dried, fiercely hot or smoky and subtle, each type of chilli from chipotle to habanero has a different role to play in food. Stevie and Emma create a mild chilli fish stew, smoky pulled pork and a chilli chocolate cake with tequila. Their journey takes them to meet chilli farmers who play music to their crops, a Zapotec cook with a recipe handed down from 500BC and a guardian of the nation's best kept culinary secret, mole negro.