Marinate the chicken - Whisk the yogurt and salt together, until creamy and thoroughly combined in a large bowl Lightly score the chicken thighs so that the marinade can be easily absorbed. Add the chicken to the marinade and mix thoroughly making sure that each piece is coated thoroughly. Marinate at least one hour to overnight.
Make the biresta (fried onions) – Heat the oil and ghee over medium high heat in a medium dutch oven until almost smoking. Add the thinly sliced onions and sauté until a light golden brown. Remove the fried onions from the oil with a slotted spoon and place the fried onions on a paper towel and spread out. Set aside dutch oven with the flavored oil for later use - about 5 minutes.
Blend the korma sauce mix - Add all the ingredients together into a blender and blend until smooth. Set aside
Blend the raisin and nut paste - Add all the ingredients together and 1/4 cup of the biresta into a blender and blend until smooth. Set aside.
Temper the whole spices - Heat the biresta oil over medium heat. Add the whole spices and sauté until fragrant - about 30 seconds
Fry the korma sauce until the oil separates - Add the korma sauce and saute until all the water evaporates and the oil rises to the top of the sauce - about 2-4 minutes
Cook the marinated chicken in the sauce - Add the marinated chicken to the simmering korma sauce and mix thoroughly. Reduce flame to medium low and cook. Add another 1/4 cup of water if the sauce looks really dry. Mix and cook for about 2 minutes. Add the dried fruit and nut paste. Mix well. Simmer for about 15 minutes on medium to medium-high heat, stirring from the bottom occasionally. If it looks like the chicken is breaking apart, swirl the pot to move the sauce instead of stirring the pot. Add all the finishing ingredients and mix well. Put the lid on the pot and turn off the heat. All the korma to rest for 10 minutes - do not open the lid during this time.
Garnish and serve - Sprinkle the remaining biresta and sliced almonds on top of the korma and serve immediately.