You are welcome to skip the step of sautéing the eggplant separately, and instead simmer it in the gravy. However, please note that the brinjals will need time to cook all the way through, so you should add more water to the gravy if you plan on cooking it this way. Add the brinjals to the gravy, cover, and cook until knife-tender. Be sure to stir every 3 to 4 minutes to keep the masala from sticking to the pan and burning.