While the recipe uses turmeric instead of saffron, you can use saffron instead of the turmeric. Note that you need less saffron than turmeric, and you also need to add it later in the process so as not to burn it.
To get started, heat up some olive oil in a large pan. Then sauté the minced garlic, rice, onions, and carrots. Once the rice is looking browned, add in the broth. Like the kebsa, make sure to be stirring to keep rice from burning or sticking to the pan, and to make sure it doesn’t dry out (use a lid when not stirring). Once the broth is in, add the turmeric, paprika, and tomato. Keep in mind that since the turmeric and paprika are your only spices here, you’ll want a decent amount of each (around a teaspoon per cup of rice).
Once the rice is coming along nicely, add the green beans (if your adding them). Then once the rice is looking good, stir in the lemon wedges (or juice) and then add your shrimp, crawfish, and any other shellfish you’ve added.