From what I can see, there are a couple things that came into play in this challenge. The first, and I said it in tonight's episode, is if you put good food into the box, you'll get good food out. Incidentally, this rule also applies to stocks, stews, kid food, and all other things that people assume will somehow miraculously turn out fine even in the absence of high quality ingredients. So, the need for good ingredients was a given.
Second, was the need to winnow those ingredients down to fit the parameters of cooking on a plane. Everything was going into a tiny convection oven for a minimum of ten minutes. Whatever item the chefs chose was going to have to be something that was actually improved by this rapid blast of dry heat. There would be no room for gentle basting, a slow simmer, or coaxing out flavor with handfuls of fresh herbs. The skill here was going to be in choosing what to cook, and then executing with precision, since all the proteins and vegetables would need to be prepped so that everything cooked at the same rate. Thus, both the consistency of the food itself (i.e. an oily fish, versus a drier, flaky one) and the consistency of the prep work were important factors.