I have a 1.5 lb piece of meat cut from inside a roast leg of lamb, cooked med rare. How do I marinate it well to use in a Biryani or Curry dish?

Hi Mari! Here's a guide on how to build a biryani: https://food52.com/blog/14242-how-to-make-biryani-without-a-recipe

And here's a recipe for a marinated lamb curry: https://food52.com/recipes/32664-the-best-indian-lamb-curry