In a large bowl, coat the chicken with a drizzle (approximately 1 tbsp) of olive oil and season with salt and pepper. Then coat chicken with the garlic powder, smoked paprika, mustard powder, and fresh oregano. Toss thoroughly to combine and let rest for a moment while the oven preheats (this lets the flavor marinate a bit better).
Preheat oven to 375ยบ F. Line a baking sheet with tin foil or parchment paper.
Place chicken on the prepared baking sheet. Roast for approximately 45 minutes, or until chicken is deep golden-brown and getting crispy. Every 10-20 minutes, baste the chicken with its drippings using a brush or spoon.
While the chicken is roasting, prepare the peas. Bring an oven-safe saute pan (like a cast-iron skillet) to medium-low heat on the stove. Coat the pan with olive oil (about 1 tbsp), and add the minced garlic and red pepper flakes. Saute for approximately 2 minutes, or until fragrant. Add the peas and season with salt and pepper. Saute for 5-8 minutes more, or until peas are softening and hot. Remove from the heat.
Using a fork or potato masher, smash the peas until about two-thirds are split.
Once chicken is done, turn the oven off but close the oven door quickly so that it retains some of its heat. Then, take each thigh and nestle it into the prepared smashed peas right in the skillet. Squeeze half of one lemon over the whole dish and drizzle any dripping from the roasting pan on top. Place the chicken and peas in the warm oven and let the chicken rest for 10-15 minutes.
Once done resting, top the dish with handfuls of chopped fresh mint. Serve hot with salad or rice. Enjoy!