Wash the meat and put it in a medium size pot (deezee for traditionalists), half filled with water, add the beans, the onion, turmeric, salt and pepper and let it cook for 1-2 hours on medium-low heat.
Next, add the potato, rice, and the tomato (they get too soft too soon if you add them at the beginning), and let it cook on low heat until all the ingredients are soft.
Take the pot out, separate the juice from the ingredients and pour the ingredients in a bowl, separate the bones and using a potato masher (gousht-coob) or something similar, finely mash the whole mixture.
Taste a small portion and add more salt/pepper if needed.
When the mixture has a smooth texture, it can be served.
The soup (juice) is also served in a separate bawl.
The idea is to mix it with small pieces of bread (not American bread loaves, more like pita bread, tortilla bread, or any kind of Iranian bread you can find in specialty stores).
Notes: Soak the dried beans and the rice before hand.
It speeds up the cooking process.
The best kind of meat for this dish is what is called muscle meat (mAheecheh) which has plenty of meat, fat, and bones (the name used to refer to it escapes me unfortunately. Shank maybe?).
The tomato, potato, and the rice are all optional.
They give richer flavor, color and texture to this dish.
In more traditional versions they don't use any of these ingredients.
While mashing the ingredients, you can also add finely chopped raw onions.
The onion juice gets mixed in and gives it a different flavor.
At the table, this dish is served with Iranian bread, raw onions, radishes and fresh herbs such as parsley, basil leaves, mint leaves, leeks, etc.