For the optimized office worker looking for the trifecta of fast, healthy and filling, few meals are more efficient than a pile of veggies and some dressing swirled with tofu or grilled chicken. Unfortunately, the aspirations of a salad are often dashed by the difficulty of making one that is actually good. The ingredients come from every corner of the supermarket, and if they aren’t combined in the right proportions, or if they are made too far in advance, every bite is a drag.Ms. Silverglide, 42, the chief executive of Mixt, tried to solve this problem with a setup in which customers proceeded down a counter and called out i …
