Chicken Chargha (Whole Chicken Steam Roast)

Instructions
Prepare chicken: Rinse chicken inside out thoroughly. If you're not brining, drain and pat dry. Make 3-5 slanted cuts (about 1” deep) into the breasts, and 2-3 cuts into the legs, trying not to get to the bone. Then turn over and make a few slits on the less meaty side.
Brine: In a large bowl, dissolve the salt and vinegar in 3 quarts (12 cups) water. (Keep stirring until salt is completely dissolved.) Submerge the chicken in the water. Cover and allow to sit on the counter for at least 30 minutes, up to 2 hours. If brining longer (up to overnight), place in the fridge. Remove the chicken from the brine and drain the water. Pat the chicken dry to prevent diluting the marinade.

Marinate: Combine all the ingredients listed under 'Marinade' in a medium bowl. Coat the chicken with the marinade, making sure to get in the cuts and crevices. Stuff any leftover marinade into the cavity and place it breast side-down. Cover and refrigerate for at least 6 hours, up to 48 hours.

Preheat oven:, take out the chicken, of the fridge and allow it to come closer to room temperature. Preheat the oven to 325°F/165°C.
2 medium (~500 g) potatoes, peeled and cut into medium-sized cubes or wedges (~2”)
1/2 medium (~100 g) red onion, halved vertically, then cut into in 1/2-inch wedges
2 tbsp + 1/4 cup neutral oil, divided
2 tbsp salted butter, optional
1 tsp chaat masala, plus more for sprinkling

Roast/Steam: Place the potatoes and onion wedges in a deep, oven-safe roasting pan. Place the chicken breast side up and brush the remaining thick marinade over it (discard any liquidy marinade). Tie the legs using twine or an oven-safe silicone band. Drizzle 2 tbsp of oil on top of the chicken and vegetables. Cover the pot with a lid or seal with aluminum foil to create steam (dum). Roast for 60-70 minutes, until the chicken is cooked through and tender (165+°F Internal temperature). Remove from the oven and allow to rest for 10 minutes, until cool enough to handle.

Pan-Fry Chicken: Heat the remaining 1/4 cup oil and butter (if using) in a large nonstick pan over med-high heat. Using your hands or tongs and wooden spoon, gently lift the whole chicken and place it in the oil. Cook the chicken for 3 minutes, breast side up. Tilt the pan and use a ladle to scoop the oil and pour it on the top and sides of the chicken. Carefully turn over the chicken and pan-fry the bottom, breast side down, until lightly golden and seared, 2-3 minutes. Sprinkle 1/2 tsp of the chaat masala over the chicken. Using tongs to grab the sides, carefully lift the chicken and place it on a serving tray, breast side up. Sprinkle with the remaining 1/2 tsp of chaat masala.
Pan-fry Vegetables: Next, use a slotted spoon or tongs to transfer the potatoes and onions to the frying pan. Pan-fry for 2-3 minutes, until lightly charred. Discard the leftover roasting liquid/pan juices, or reduce it in the same pan to serve alongside. Serve with the potatoes and red onions (roasted and/or fresh), lemon wedges, and Vegetable Raita or Mint Raita.