Ingredients:
8 tablespoons vegetable oil
20 whole black peppercorns
6 whole cloves
2 whole bay leaves
6 whole cardamom pods
2 medium onions -- chopped fine
6 garlic cloves -- chopped fine
1 ginger root - (1" cube) -- chopped fine
2 pounds beef -- cut 1" cubes
1 teaspoon cumin seed
1/2 teaspoon cayenne -- (optional)
1 teaspoon ground coriander seed
2 teaspoons salt
5 tablespoons yogurt -- beaten
2 pounds chopped spinach -- fresh or frozen
1 teaspoon Garam Masala -- (recipe follows)

Garam Masala
1 teaspoon cardamom -- (seeds only)
1/2 cup whole black peppercorns
1/3 cup cumin seed
1/4 cup coriander seed
3 cinnamon sticks - (3" long)
6 whole cloves


Method:

1-Put the ginger, onions, and garlic into a blender container, and blend to a paste, adding a tablespoon of water if necessary. Set aside.
Put the peppercorns, cloves, bay leaves, and cardamom pods in one bowl. Put the ground cumin, ground coriander, cayenne and 1 teaspoon of the salt in another bowl. 
Put the yogurt into another bowl. Wash and chop and drain the fresh spinach, have it ready to add into the dish. (Or defrost the frozen spinach.) 
Put the remaining teaspoon of salt into another bowl.
Now, heat the vegetable oil in a large Dutch oven. 
When hot, put in the peppercorns, cloves, bay leaves and cardamom pods. 
Stir for a second. Now put in the onions, garlic, and ginger. 
Stir and fry until the paste starts to develop brown specks.
Add the ground cumin, ground coriander, cayenne and 1 teaspoon of the salt. Stir together, then add the meat. 
Stir and fry for a minute. 
2-Next, add the yogurt 1 teaspoon at a time, until the yogurt has been mixed throroughly with the other ingredients. Keep on frying until the meat has a slightly browned look.
Add the spinach, bit by bit, stirring in more as the spinach in the pan wilts. 
Keep stirring and cooking until the spinach wilts completely. It should give up its juices, to cook the meat.
Now, put the entire mixture in the crockpot, and allow to simmer for 6 to 8 hours on HIGH or 8 to 10 hours on LOW, until meat is tender. When done, sprinkle the garam masala over the meat, and stir in, then simmer for about 5 minutes longer. If there is too much liquid, simmer uncovered for 5 to 10 minutes until sauce is thicker. 
This is good over rice or noodles.
3-For the Garam Masala: 
Combine all ingredients and grind very fine, using a blender or a coffee grinder. 
Store unused portion in a tightly closed container with other spices.