What does it mean to caramelize?
Well, two things, actually.
When it comes to dessert, caramelizing means to heat sugar until it liquifies and turns gold to dark brown depending on its temperature (around 320 to 350F on a candy thermometer). Custards such as crème brûlée are caramelized by sprinkling them with sugar and placing them either under a broiler or salamander or by torching the sugar until it forms a brittle burnt crust. Caramelizing can also technically mean to coat a mold with caramel so that it acts as a glaze when a custard or other dessert is turned out (as in crème caramel or flan).
We also use the word caramelize to describe what happens when we brown meat over high heat to draw out its natural sugars and create a flavorful crust. Vegetables with a high natural sugar content, such as onions, carrots or turnips, can also be caramelized by sautéing them in butter and a bit of water to prevent burning. Fruit such as apples or figs can also be caramelized by sautéing them in butter before sprinkling them with sugar, which gives them a lightly caramelized glaze.