Preheat oven to 400 degrees F (200 degrees C).
Slice the Red Potato (12) into 1/2-inch slices and set aside.
Remove the Fresh Rosemary (0.25 ounce) leaves from the stems, and discard stems. Roughly chop the leaves and place in the same bowl as the potatoes.
Add Olive Oil (1 tablespoon) to the bowl along with Salt (1/4 teaspoon) and Ground Black Pepper (1/4 teaspoon). Toss to combine.
Trim the ends off of the Asparagus (8 ounce) and discard ends. Slice the asparagus into two inch diced pieces, and set aside.
Slice the Lemon (1) into 1/4-inch rounds, and set aside.
Pat the Chicken Thigh (4) dry with paper towels. Season each chicken thigh with Salt (1/4 teaspoon) and Ground Black Pepper (1/4 teaspoon).
In a large, oven-safe skillet over high heat, add Olive Oil (1 tablespoon).
When hot, add the chicken thighs and sear on each side for four minutes until golden brown. Then transfer chicken to a plate to rest.
In the same pan over high heat, add the potato mixture and saute for two minutes or until lightly browned.
Add the asparagus to the pan and toss briefly to combine.
Place the chicken on the potatoes and asparagus and then pour any of the meat juices from the plate into the pan. Add lemon slices.
Place the lid on the pan and place in the oven for fifteen minutes.
Remove the pan from the oven and set the chicken aside. Add the Unsalted Butter (2 tablespoon) to the pan and toss to combine.
In the center of two plates, place the chicken, potatoes, and asparagus. Add the lemon for decoration if desired.