In a medium pot, simmer grains in chicken stock, adding salt to taste if stock is unsalted. Different grains will cook at different rates, but 35 to 75 minutes is the general range. When grains are just tender, drain, reserving any extra stock.

In a large skillet, cook mushrooms over medium heat until crisp. Using a slotted spoon, transfer mushrooms to a plate.

Add onion, pepper, celery and ½ teaspoon salt to skillet and cook until vegetables are translucent, about 7 minutes. Add garlic and thyme and cook for 2 minutes longer, until garlic is fragrant.

Stir beans, black pepper and nutmeg into skillet and cook until vegetables are very tender, 10 to 20 minutes, adding some reserved chicken stock from the grains or water if pan looks dry.

Add drained grains to pan and stir until heated through, adding more stock or water if needed. Stir in mushrooms, and salt to taste. Serve grains and beans topped with celery and thyme leaves, with hot sauce on the side.