Tonka beans. Fruit of the leguminous Cumaru tree (Dipteryx odorata), native to Central America and also exploited for its beautiful timber. They look like wizened troll nuts but I won't hold that against them. Tonka is familiar to most perfume fanatics and the note features heavily in the whacky Orientals I tend to favour (Serge Lutens et al), so it wasn't exactly a stranger when I unscrewed the bottle I received the other day.
The scent in its raw form bothered the shit out of me with another, more elusive association until I remembered the infernal mellow savour of roll-your-own fags and confirmed via the Wiki page that tonka is heavily employed by the tobacco industry.
Next to tonka, raw vanilla is a much higher, narrower note, more exclusively of itself, silver-clean, far more densely floral (like a waxy wad of compacted orchid flowers) and possessing that odd, dusty, astringent tang that is really only faintly caramel.
If my island pods are pretty pungent on the vanilla scale, tonka is easily twice as strong, with a huge, low, malty punch (like bagged horse feed), notes of molasses, sweet wood shavings, wet grain and distant pouch tobacco. There's something else in there too- I get scuffed black and realise it's the smell of vanilla pod skin, bruised and scraped of its seeds by a knife, that faint leathery note that is quite independent of its haughty floral payload.
It's in those darker corners that their alleged relationship lies because their similarities are otherwise tenuous during real-time comparison. They both suggest sweet but that's facile association rather than accurate characterisation.
Tonka is touted as a vanilla replacement and while you probably can switch one for the other in most recipes, medium to high-functioning palates should brace themselves for what possibly constitutes prohibitive difference. I grated a third of a bean into oven-top hot chocolates; the result was loud, malty and well, tonka rather than vanilla and the grated shavings, though fine, were a persistent presence. The overall effect is far less subtle and elevated than pod vanilla and probably most suited to those robust dishes involving caramel and Asian flavours.
So to cut a lot of wank short, tonka is nice but not really a vanilla analogue and its distinct properties deserve their own consideration.
Below left: a third of a large bean's worth of grated shavings. Right: 15g of tonka beans.