Tonka beans are an exotic ingredient — once associated with French haute cuisine, but now creeping into more and more home pantries. The beans are about an inch-long, and resemble a woody raisin, with a lacquered, wrinkled exterior, and softer brown centre. Tonka's most distinctive feature though is their enormous potency — heady vanilla flavours, with oily clove aromas, and perfumed magnolia, sandalwood notes.
The beans grow on the flowering Cumaru tree, most often found in Venezuela, Guyana, Brazil and other countries throughout north-east region of South America. Tonka's strong scent means that it has been coveted by the perfume industry for centuries — starring in world-renowned products.
The tonka bean smell comes from a chemical compound called 'coumarin'. As there's an all-out ban on any ingredients containing coumarin in America, there is lots of misinformation circulating about tonka beans' toxicity. The reality is that it would take the equivalent of 30 whole tonka beans for the coumarin levels to become dangerous — and as the shavings of a single bean stretch to round 25-50 servings, cooks shouldn't lose too much sleep over it. Tonka beans aren't yet a mainstream ingredient, so online spice specialists are the best place to track them down. Use sparingly, and store the tonka beans in a tightly-sealed container, as you would with any other spice.