Preheat oven to 425 degrees F. In a medium bowl, combine the remaining 4 tablespoons olive oil, the mustard, garlic, shallot, rosemary, paprika, lemon zest, lemon juice, and a pinch each of salt and pepper. Add the chicken and toss well to combine. Let sit 15-20 minutes. On a rimmed baking sheet, toss the potatoes with 2 tablespoons olive oil and the sesame seeds. Season with salt and black pepper. Roast for 20 minutes, or until tender. Remove the potatoes from the oven and push them to one side of the pan. Put the chicken on the other side. Arrange asparagus around the chicken. Drizzle over 1 tablespoon olive oil, season with salt and pepper. Return the pan to oven and roast for 20-25 minutes more, until the chicken is cooked through. Meanwhile, make the feta. Combine the feta, yogurt, garlic, and lemon juice in a blender and blend until smooth and creamy. Stir in the herbs, paprika, and a pinch of red pepper flakes. If desired, thin with additional lemon juice. To serve, divide the chicken, potatoes, and asparagus between plates. Spoon the feta sauce over the chicken. Eat and enjoy!