What you’ve really come across is a recipe writer who loves to micromanage, or is in love with his own tastebuds and must, simply must, share his wonderful knowledge and wisdom and taste with you (and who assumes that you, too, can learn to be a food snob). There’s no excuse for not telling you in the recipe that Fleur de Sel is a relatively expensive French sea salt.
Fleur de Sel is harvested by hand off the village of Guerande in Brittany in July and August, when the sea is calm and the weather conditions are just right. It is a lovely salt, but only the extravagant use it for cooking. Most people use it as a condiment and sprinkle a pinch here and there in places where the salt will shine and its distinctive flavor and texture will be appreciated. Fresh bread with unsalted butter and a sprinkle of Fleur de Sel is a favorite use. We enjoy a little on the top of a plain omelet.
It’s per-pound price is a little over $20, but it is sold in small quantities that won’t require a second mortgage. Apparently there are fraudulent fleurs flooding the market these days, so you may stumble upon a bargain price, but it might not be the real thing.
If the carrot recipe in question calls for Fleur de Sel in the cooking, substitute kosher salt. If it is to be sprinkled on at the last minute, the pure taste of a good crumbly sea salt can add a lot to the dish. If not Fleur de Sel and if not today, you should still consider purchasing a fine sea salt for use as a condiment. Considering the flavor they provide, on a pinch-by-pinch basis, a good sea salt can certainly be a reasonable investment in your cooking.