Preheat Oven and Cook Quinoa: Preheat oven to 400 degrees, place veggie stock, quinoa, 1 cup water and a pinch of salt in a small pot. Bring to a boil, cover and reduce to a simmer until tender, 15-20 minutes.
Prep and Cook Chicken: Wash and dry all produce. Shell and roughly chop pustachios. Pat chicken dry with paper towel, and place on a lightly oiled baking sheet. Season with salt and pepper. Evenly spread a thin layer of mustard on top of chicken. Press pistachios into mustard. Bake until no longer pink in center, about 20 minutes.
Make Salad: While chicken cooks dice cucumber and tomato. Chop mint leaves, saving 1 tbsp for garnish. Halve, peel, and finely dice2 tbsp shallot. Zest and halve lime. Dice jalapeno, removing ribs, and seeds for less heat. Combine everything in a medium bowl. Toss with a squeeze of lime and drizzle with olive oil. Season with salt and pepper.
Slice Chicken: When chicken is cooked enough, remove from oven and rest 3 minutes before thinly slicing.
Season Quinoa: When quinoa is ready, fluff with a fork and season with salt and pepper. Stir in a drizzle of sherry vinegar and drizzle of olive oil.
Plate: Serve chicken on a bed of quinoa. Spoon cucumber jalapeno salad on top and garnish with reserved mint.