How to Make It
In a large saucepan, combine the beans with the thyme and 2 of the garlic cloves. Cover with water and simmer over moderate heat until the beans are just tender, about 25 minutes. Season with salt and black pepper and let cool slightly in the liquid.
Meanwhile, in a food processor, combine the parsley, cilantro and the remaining garlic clove and pulse until chopped. Add the lemon juice and 1/2 cup of the olive oil and puree until smooth. Scrape the charmoula into a bowl. Stir in the ground coriander and cumin and season with salt and black pepper.
In a large skillet, heat the remaining 1/4 cup of olive oil until shimmering. Add the oyster mushrooms, season with salt and pepper and cook over moderately high heat, stirring occasionally, until browned, about 10 minutes.
Drain the beans; discard the thyme and garlic. Add the beans and beef broth to the mushrooms and cook over moderate heat until the liquid has nearly evaporated, about 15 minutes. Keep warm.
Meanwhile, heat a grill pan. Generously season the steak with salt and black pepper and brush with olive oil. Brush the peppers with oil. Grill the steak, turning occasionally, until lightly charred all over and medium-rare within, 10 to 12 minutes. Transfer the steak to a work surface and let rest. Grill the sliced peppers until softened and lightly charred, about 5 minutes.
Slice the steak across the grain and serve with the cranberry beans, mushrooms, grilled peppers and charmoula.