Add the chopped onion, sliced tomatoes, salt, roasted spice mix, ginger-garlic paste, vinegar and mustard oil to boneless chicken cubes. Mix well. Set aside for 10 minutes to marinate.
Cut the green coconut at the top, large enough to put in the marinated chicken pieces. Pour out the coconut water into a bowl. You don’t need to take out the flesh. Instead, take a spoon, scrape it inside and make a slightly smooth paste.
Stuff the marinated chicken inside the coconut.
Add 3 tablespoons of coconut water. Do the necessary adjustments to make sure that the coconut water goes inside.
Spread the aluminum foil over the open mouth of the green coconut and then seal it with the wheat dough.
Pour sand into a pan. You can use salt instead of sand.
Put a stand on the sand.
Place the green coconut on the stand.
Cover it with a large pan. Steam it for 30 minutes on a high flame. Turn off the oven. Wait for a few minutes to let it cool. (Pro Tip: Cooking time can vary with coconut size and chicken pieces. So, check that the thickest piece for doneness before turning the oven off.)
Remove the lid.
Take out the green coconut. Remove the dough and aluminum foil.
Take out the chicken stuffed inside green coconut and put it on a plate. Sprinkle the kernel over the dish. Your homemade daab chicken is ready.