Preheat oven to 400º. Coat a glass baking dish with olive oil.
Coat chicken in Dijon mustard, then panko crumbs. Transfer to the baking dish.
Cook your rice or quinoa as directed.
Bake chicken for 12-14 minutes.
While that cooks, combine 1/4 cup olive oil, juice from 1 lemon, & salt & pepper and mix. This is your sauce. You may have to adjust slightly (ie: add salt, more lemon, etc.).
In a large bowl, create a bed of rice, then add a handful of arugula, then top with your chicken. I like to slice mine.
Sprinkle some fresh grated cheese.
Drizzle your sauce over everything.