The tonka bean's complex aromas commend it to both chefs and home cooks

​Chefs are going bonkers for tonka, and it's even popping up in supermarket desserts. Clare Hargreaves explores its complex, and potentially intoxicating, flavours

Tonka (Alamy)

They call it the most versatile and delicious ingredient you've never heard of. Its gorgeous aromas are so complex they'll send your taste buds into a tailspin: there's heady vanilla, tropical coconut, sour cherry, bitter almond, oily clove and liquorice, and sweet hay, all at once. It's as much at home in milk puddings as with sweet fruits, chocolate and scallops. In America it's banned – which only adds to its thrill.

The miraculous food I'm talking about is the tonka bean, the flat, wrinkled black seed of the flowering cumaru tree grown in South America. Roughly an inch long and shaped like an almond, it looks like a cross between a woody raisin and a prune. Chefs can't get enough of the bean, often using it as an alternative to vanilla pods. “Tonka is less sweet than vanilla and much more complex and fragrant,” says James Ransome, who sources tonka beans from Brazil to sell online through The Spicery. “Don't be deceived by the price tag, as a little goes a long way.”

Having spread through Paris, la fièvre tonka (a play on fève tonka, the French for tonka bean) has been taking hold in British restaurants, too. At her Mayfair restaurant, Murano, Angela Hartnett serves a pear tarte tatin with a tonka bean crème anglaise. “It's a nice twist on the usual vanilla anglaise with apple tarte tatin,” she says. Chris Harrod, the Michelin-starred chef patron of The Whitebrook, in South Wales, loves tonka bean ice cream with poached apricots. “The flavour is much more interesting than vanilla,” he says. Ryan Simpson, of Orwells, in Binfield Heath, pairs tonka bean ice cream or panna cotta with poached or sorbeted rhubarb. “I came across tonka when working for Troisgros in France,” he tells me. “It's been used in French cooking for years.” At The Modern Pantry, in central London, Anna Hansen infuses fruit syrups with tonka to produce a sour cocktail and she grates tonka into her breakfast hazelnut croissants. For Christmas, she makes a stunning chestnut and tonka bean purée as well as a tonka mincemeat (containing grated tonka, along with the usual spices) that she's selling in her deli. “Tonka gives it a unique flavour,” she enthuses. “Amazingly the tonka stands out from the other spices – and enhances them.”

Now, the tonka bean's magical aromas are wafting through home kitchens, too. Taking their lead from chefs, adventurous cooks are using the indulgent black beans to infuse panna cotta, crème brûlée, ice cream or stewed fruit. Some are grating it into crumble toppings or into bread-and-butter pudding. Tonka is also lovely in savoury dishes such as scallops, bread, savoury soufflés and sorbets, even mayonnaise. Toast the beans lightly to enhance their flavour, then finely grate them with a nutmeg grater.

If that all sounds like too much faff, use whole beans to infuse spirits or sugar syrups. Or pop a bean into a jar of sugar as you would a vanilla pod to infuse it with exciting new flavours.

Supermarket pâtissiers are also picking up on the tonka trend and selling us tonka-infused desserts. Marks & Spencer has just launched its “Milk Chocolate, Raspberry and Tonka Bean Bar” (a dark chocolate brownie topped with raspberry jelly and milk chocolate tonka-flavoured mousse and milk chocolate). The store also includes a tonka macaroon in its gift box selection. Sales of both have been so brisk that James Campbell, M&S's desserts king, says he's now looking into other tonka products.

Cool beans: Anna Hansen, the chef at The Modern Pantry, in London, infuses fruit syrups with tonka to create a sour cocktail, and grates it into her Christmas mincemeat, too

“The tonka bean has a unique flavour… with interesting spice and fruity notes,” Campbell says. “It has a strong aroma so only a very small amount is needed to give a delicious, subtle taste. We use it in our chocolate, raspberry and tonka bean bar as it adds a spicy vanilla depth which works beautifully with the rich chocolate.”

Tonka gets its fragrance from a chemical compound called coumarin. As well as being used to flavour food, coumarin is used in perfumes and other toiletries, candles and even tobacco. Interestingly, high levels of coumarin are also contained in a number of fragrant plants commonly found in Britain, including sweet woodruff (sometimes used by chefs as a vanilla/tonka alternative), sweet grass, cassia cinnamon, and sweet clover.

If you live in the United States, however, tonka's heavenly flavours might never thrill your taste buds. The bean is banned there due to coumarin being toxic if eaten in large quantities. But the crazy thing, critics say, is that it never is: you'd need to eat at least 30 whole tonka beans to reach the coumarin level – 1g – thought to be toxic. The same would apply to plenty of other foods we happily eat, from nutmeg to poppy seeds and cyanide-packed apple pips. When it comes to tonka, I, for one, am more than happy to take the risk. Perhaps the fact that it's a forbidden fruit in some parts makes it all the more enticing. Will you join me?

Buy tonka at thespicery.com; souschef.co.uk; steenbergs.co.uk; foxs-spices.co.uk

Ways with tonka

* Infuse milk/cream to make tonka custard, ice cream or panna cotta – great with stewed fruits. Grate if you like a flecked look, or infuse with a whole bean if you prefer a clean look.

* Grate beans into crumble toppings – good with acidic fruits such as rhubarb, apple and gooseberry.

* Pop a bean into the saucepan when poaching plums or pears.

* Infuse alcohol or fruit syrups with tonka to make cocktails with an unusual twist. Great with whisky, cognac, sherry or Grand Marnier.

* Grate it into scones, breads and croissants. Or blend with your other spices in a bread-and-butter pudding.

* Grate it into mayonnaise, to accompany fish, or shave it over scallops.

* Pop a tonka bean into a beef stew to give extra depth of flavour.

* For an extra kick, grate it into a purée of carrot, Jerusalem artichoke or parsnip, along with a generous dollop of butter.

* Pop a bean into a jar of sugar, as you would a vanilla pod, to infuse it – dunk your doughnuts in it to give them an unusual flavour.

Tonka bean chocolate pots

Tonka Bean Chocolate Pots

thespicery.com

Serves 4

350ml double cream

100g decent-quality dark chocolate

1 tablespoon sugar

3 tonka beans, broken in halves

Heat the cream together with the tonka beans and a tablespoon of sugar. Bring to the boil, then immediately turn the heat right down to the lowest setting.

Break the chocolate into chunks and put them into a heatproof bowl.

Place the bowl over the pan of cream (without the bottom of the bowl touching the hot liquid) and heat very gently until the chocolate melts.

Strain the infused cream through a sieve into the melted chocolate, stirring all the time until you have a nice smooth mixture.

Pour into small cups or dishes (espresso cups are ideal) and refrigerate for at least a couple of hours to set. Let the pots come to room temperature before serving. Decorate with tonka beans if you like, but make sure to remove them before eating.