Which of the following is required for blanching nettles?

Blanching nettles involves briefly cooking them in boiling water before shocking them in ice water to stop the cooking process. This method is essential for several reasons: it reduces the bitterness of the nettles, helps to soften their texture, and neutralizes their stinging properties due to the presence of oxalic acid. By immersing nettles in boiling water, you effectively deactivate these compounds, making the nettles safe and palatable for consumption.

Cold water, hot oil, and vinegar do not fulfill the requirements for blanching. Cold water is typically used for shocking the cooked vegetables but does not cook or soften them. Hot oil is more suited for frying or sautéing, not blanching. Vinegar can be used in pickling or adding acidity to a dish but is not part of the blanching process. Thus, boiling water is the essential component for properly blanching nettles.