Tommi has a whole book paying homage to the humble chilli pepper, "Chilli notes". Here's a selection from Tommi's Chilli Hot List to give you a tongue tingling taste.
RICH & MILD
Poblano chillies are large fresh chillies. similar in appearance to green peppers but a much darker green and with a thinner skin. When dried, a poblano is transformed into the ancho chilli, a round, dark red chilli with fruity tones. Rich in flavour and fairly mild in heat (although they are steadily getting hotter), an ancho adds sweetness and depth of flavour to marinades, salsas and moles.
HERBACEOUS & RAISINY
Pasilla chillies have a herbaceous, raisin-like taste with undertones of tobacco that adds huge complexity to food. In Mexico they are part of the chilli trio used to make moles (with the ancho and the guajillo) but they are also wonderful on their own thanks to their unique flavour. Try them out in my dark, squidgy chocolate brownies or shin of beef. You will be bowled over by their flavour.
CURVY & FRESH
Green, curvy, fresh and spicy, these fiery chillies can pack quite a punch, although the heat won't last long (and can vary hugely from one chilli to another). Jalapeños are increasingly available in supermarkets and are hotter than the unnamed fresh chillies of a similar size that you see sold next to them.
SMOKY & FIERY
The chipotle, or smoked, dried jalapeño, is probably one of Mexico's best-known chillies (its name stems from the words "chilli' and 'smoke' in the native Indian language Nahuatl). Although there are several different varieties of chipotle, the one that I use is known as the mora. It has an intoxicating fiery flavour that is delicious in salsas and mayonnaises and makes the incredible chipotles en adobo that can quickly become an indispensable ingredient in your cupboard.
I use chile de árbol (named after the treelike bush it grows from) like other people use black pepper. It has a wonderfully versatile dry, fiery heat that adds a touch of peppery seasoning to stocks, stews and sauces. Whilst chiles de árbol are hot, using one in a large soup or stew will add only a gentle peppery heat through the dish; if you wanted a really hot dish you might add two. When toasted, more of their flavour comes out and they become wonderfully nutty; they are a fail safe variety to use for making chilli oil and hot chilli sauces. You see this chilli cropping up all over restaurant menus in California where influences from Mexico (and Korea) merge with the modern, seasonal approach to food first espoused by Alice Waters thirty years ago.
HOT & FRUITY
Habaneros are from the Yucatan and are the first Mexican chilli to win Protected Denomination of Origin status. They are almost identical in appearance and flavour to the Scotch bonnet and look like brightly coloured Chinese lanterns, in orange, red and yellow. Whilst they are pretty to look at they are devilishly hot with a wonderful citrusy note to them that is accentuated with roasting. Eat judiciously.
Chilli Notes by Thomasina Miers
Published by Hodder & Stoughton.