Start by coating the salmon fillets in the garlic powder, ginger, chilli powder and coriander and a sprinkling of salt and pepper. Set aside.
Make the peanut sauce by heating the vegetable oil over a medium heat. Add the garlic and cook for a couple of minutes then add the curry powder, cayenne, chilli and garlic powder and cook for another minute. Pour in the coconut milk along with the brown sugar and peanut butter. Bring to the boil and simmer for 10 minutes until it's thickened.
While the sauce is thickening heat a tablespoon of vegetable oil over a high heat in a frying pan. Cook the salmon fillets skin side down first being careful not to move it around too much so that you get lovely crispy skin. After about 5 minutes flip the salmon fillet and cook for another couple of minutes on the other side (how long will depend on the thickness of your salmon). Remove from the pan.
Once you've removed your salmon fillets from the frying pan, add the pak choi, cut side down, and cook for a couple of minutes until wilted. Finish the sauce by stirring through the sesame oil. Serve the salmon and pak choi on udon noodles with the sauce on top. Sprinkle over sesame seeds, chopped peanuts and coriander.