Add the fava beans to a pressure cooker, add enough water to generously cover the fava beans, set the cooking time for the option “beans”.
NOTE: If you’re using canned cooked fava beans you can skip this step.
Meanwhile, prepare the foul medames sauce:
Add olive oil to a pot, set the flame to medium, and when hot, add the spices, let them sizzle for a few seconds. Be very careful not to burn the spices since they are very delicate.
Add the minced onions, add a splash of water and sauté the onions for a few minutes.
Add the garlic, stir for 40 seconds, then add the tomatoes, the optional tomato sauce, another splash of water, and salt.
Let the sauce cook on a lower flame, add water occasionally if needed.
Once the fava beans are cooked, drain them and add them to the sauce, then let them cook for a few minutes in the sauce so the flavors properly incorporate.
Turn off the heat, and with the help of a potato masher, mash the fava beans, then add the olive oil, the harissa paste, lemon juice and adjust the salt, if needed.
Transfer the foul to a serving plate, garnish it with the onions, tomatoes, cucumbers, parsley, sumac, and a drizzle of olive oil.