About 3 cups cooked short grain brown rice
1 sweet potato, peeled and thinly sliced
1 can black beans, rinsed and drained
1/2 cup coconut milk
1/2 cup frozen spinach (or 2 cups fresh spinach)
1 cup crumbled feta cheese
3 cloves garlic, crushed
1 Tablespoon lime juice
1 teaspoon of the following:
Sea salt
Pepper
Thyme
Dill
Paprika
Basil
Onion powder
Cumin
Sugar
2 teaspoons coriander
1/2 teaspoon cayenne pepper

Bring the black beans, coconut milk, and spices to a boil, then turn it down to a simmer for about 30 minutes.  Add the spinach and simmer about 10-15 minutes more.
To layer the gratin: grease a baking dish, then put about 1/3rd of the rice, followed by 1/3rd of the sweet potato slices, then a third of the black bean mixture, then feta.  Repeat until all your ingredients are gone, ending with a solid sprinkling of feta cheese.  Bake on 350 for about 45 minutes, broil for the last 5-7 minutes to get the cheese lightly browned.