Hi, msgfree. I really like Kris Dhillon's Sag Paneer. I don't see why you couldn't substitute prawns for the paneer. (She also has a recipe for Sag Meat, but that doesn't sound as good.) I follow the recipe almost exactly, (chilli to taste), keeping in mind that Kris' measurements call for slightly rounded spoonsful, and cups are 5 oz. teacups. My one change is that I add about 1/2 cup cream to the pureed spinach at the end to make it rich and creamy and good.
-Mary