1, Preheat and prep. Wash and dry all produce. Adjust rack to upper position and preheat oven to 450 degrees. Pick fronds from dill; discard stems. Finely chop fronds. Cut potatoes into 1/2 inch cubes.
2, Roast potatoes. Toss potatoes on a baking sheet with a dizzle of oil and a pinch of salt and pepper. Roast is oven into tender and lightly browned, 22-25 minutes, tossing halfway through.
3. Cook chicken. Heat a dizzle of oil is a large pan over medium heat. Pat chicken dry with a paper towel. Season all over with salt and pepper. Add to pan and cook until no longer pink in the center, 4-6 minutes per side. Remove chicken from pan and set aside. Remove pan from heat.
4. Roast green beans. While chicken cooks, toss green beans on another baking sheet with a dizzle of oil and pinch of salt and pepper. Roast in oven until tender, 10-12 minutes.
5. Make sauce. Add 1 tsp dill, sour cream, stock concentrate, mustard, and 2 TBSP water to pan used for chicken off heat. Stir, scraping up any browned bits on bottom. Season with salt and pepper. TIP: If sauce seems thick, add more water, 1 tsp at a time, until has a drizzly consistency.
6. Plate and serve.Thinly slice chicken, then divide between plates along with potatoes and green beans. Dizzle sauce over everything. Garnish with remaining dill (to taste).