Like other meal-kit-in-a-box startups, Blue Apron is premised on convenience. But the company has always argued that their model has another benefit—slashing food waste. Each meal comes with only the precise amount needed for each ingredient, whether it’s a single carrot, three dates, or a tiny amount of flour. In theory, you’ll eat all of it. In a recent study, the company asked sustainability nonprofit BSR to independently look at the data, and calculate how…