Preheat oven to 425 degrees.
Mix together ingredients for the sauce & set aside.
To a large sheet pan add the potatoes, carrots & yellow onion, then pour ⅓ of the dressing over top and toss. Bake in the oven for 25 minutes, or until potatoes are slightly tender.
Meanwhile, toss sliced chicken in oil & a few tablespoons of the lemon dill sauce.
Arrange chicken and asparagus onto sheet pan, adding lemon slices if desired, and place back in the oven to bake for an additional 25-30 minutes. if using chicken thighs, adjust time accordingly Turn to broil for the last 2-3 minutes to get a slight crisp.
Remove from the oven and drizzle with more sauce & toss. Garnish with extra dill, if desired, then serve.
