But our first task is to go to the Old Siem Reap Market and select the food we're about to cook. Although I've already tried haggling for silk scarves, toys and embroidered purses, this visit is more exciting. More than half the spices and vegetables are totally new to me. The stench of blood and innards mixed with spices makes us gag as Navin leads us past glistening flat river fish, rough-cut yellow-skinned chooks and sinewy meat. There's not much fat on anything.
The fruit and vegetables are just as exotic. Piles of durian, green mangoes, paw paw and green and brown coconuts, plus twisted aromatic roots that Navin says are expensive, lie alongside stacks of long, thin green beans. The banks of spices including chillis of every shape, colour and size and tiny limes that flavour most meals, are a rainbow against the mounds of fresh, peppery-tasting Cambodian basil and coriander.
Navin selects fish, onions, kaffir lime leaves and a chunk of gnarled root. It's called galangal and apparently tastes like ginger, but with a spicy edge that scents most Cambodian dishes. Once you recognise it you can taste it in everything.
Back at the rooftop cook school it's on with the chef hats and aprons and down to work. I'm slicing cabbage, shallots, lime leaves and carrots for our shrimp wraps. Despite years of cooking I'm clumsy and slow alongside the deft Navin. Diana gets to make the palm sugar, lime and chilli dressing.
Like all women, we chat as we cook. Navin is 25. She has a 5-month-old baby back home, being looked after by her family. She's still breastfeeding. She wakes her daughter before she leaves for work at 6.30am and feeds her again when she gets home around 6pm. It's a 12-hour work day, most of it on her feet, with 10 minutes off for lunch. The pay is US$20 ($24) a week.
Marriage breakup is common in Cambodia where sex before marriage is frowned upon and the married couple traditionally live with the bride's parents. Young husbands (referred to as "party boys") often buck a system that nails them down too early and run away, leaving their wives with two or three children, and condemned to a life of drudgery.
There are many like Navin: slender, sweet-faced young women who work 10-12 hour days as cleaners, waiters and chefs, then go home to a baby waiting for its night feed. And unbelievably, according to the girls I meet, they're considered over the hill after 30, by Cambodian men.
Although Navin grumbles a bit, she laughs much more. Soon she and Diana, who speaks reasonably fluent Khmer, are giggling away as I pound the spices with an outsized pestle and mortar.
Diana runs Bloom, a "social enterprise" organisation that attempts to help women out of poverty by employing them to make and sell stylish handbags from recycled rice sacks and silk off-cuts. Though the average wage is officially US$40-60 for a 48-hour week, Bloom's Cambodian workers get US$70 for 40 hours plus 28 days holiday a year. "Even so," says Diana, "it's taken a while for the Cambodian team to understand how to work according to international standards. But after four years, they're getting there."
She is talking about work ethics most New Zealanders take for granted such as keeping the door open so that customers know the shop is open, turning up for work on time, not raiding the till or cheating the boss.
The restaurant business, including the growing cook-school trade, is already a sizeable source of work and revenue in entrepreneurial Siem Reap. Five years ago, says Diana, there were half a dozen restaurants in the Old Town. Now there are hundreds, and several of them offer cooking schools too. You can learn practically anything here. I also tried pottery classes and have a respectable, though lumpy, green bowl and beaker (which were allowed back to New Zealand in their woven leaf box) to prove it.
Pounding spices with dried fish and fish pastes is a cornerstone of Khmer cooking. By halfway through our class, I'm having a go at lemon grass, saffron, galangal, lime leaves and rind, turmeric and something they call amomum zingiber (but which Google suggests is ginger) in a large pestle and mortar.
It's for the dish "fish amok" and needs a huge thumping to get it smooth enough for Navin, who kindly moves me on to slicing a couple of bell peppers while she grinds it into submission.
Next the spice paste is flopped into the wok with coconut cream and browned quickly before adding the sliced mud fish, salt, fish sauce, more coconut milk and sugar.
Meanwhile we're learning how to make little serving baskets out of banana leaves. As soon as the amok is finished it's spooned into these, topped with lime leaves and sliced bell peppers.
Food is a great solace for Cambodians. Although the culture was almost wiped out by the devastating Pol Pot regime that systematically worked, starved and tortured millions of people to death, traditional food and the art of cooking lives on.
It also adapts with the times. Navin's piece de resistance is sticky rice dessert. I won't go into details, save saying that the recipe involves rice, coconut milk, plenty of tinned sweetened condensed milk, more sugar and plenty of salt. And it is absolutely fabulous.
By 3pm our lesson is over, the meal prepared. We take off our hats and aprons and follow Navin downstairs to the heat and clamour of Tigre de Papier's ground floor restaurant, where Diana's husband, Alan, is hungrily waiting.
We can read it on his face. Everything we've prepared - shrimp wraps, fish amok, sticky rice - is absolutely delicious. And the whole thing, including three hours of tuition and the market visit, plus lunch, cost US$20 a head.
Click here to see the recipe for the Fish Amok created in Carroll's cooking class.
CHECKLIST
Getting there: Cathay Pacific's sister airline Dragonair offers daily flights between Hong Kong and Phnom Penh. Cathay Pacific offers special fares from New Zealand to Phnom Penh.
Getting around: Tuk-tuks are the best way to travel in Siem Reap and surrounds.
* Carroll du Chateau travelled to Siem Reap with help from Cathay Pacific.
