The following day, place fava beans in a large pot and cover with water. Add cilantro sprigs and half onion. Bring to a simmer and let cook for 50 min. to an hour or until fava beans are soft and falling apart. (Or cook in instant pot set to manual, high pressure for 20 min.)
While the fava beans are cooking, set a large sauté pan to medium heat. Add ¼ cup of water and add diced onions. Let onion cook for 3-4 minutes until tender and translucent.
Add minced garlic and jalapeño and let cook for 2 more minutes. If onion begins to stick add a little more water or veg stock to the pan.
Add diced tomatoes and cook for 5-6 minutes or until tomatoes have broken down.
Once the fava beans are cooked, add the tomato mixture to the pot and simmer for 7-8 minutes. Season with salt and pepper.
Garnish with diced tomatoes and toasted chile pasilla
You can puree the soup for a smoother texture or leave it chunky. Cooked nopales are a great addition to this soup.