Add onion with a little water to a saute pan and cook until translucent. Add more water if necessary to prevent sticking.
Over medium heat, add the garlic and lemon juice, then beans and orzo. Sprinkle spices- turmeric and pepper- over the orzo. Add water to just barely cover the orzo and cook for 10 minutes, stirring frequently.
In the last 2-3 minutes, add the spinach and mushrooms. Stir frequently while they cook gently. Do not overcook. When orzo is soft and spinach is gently wilted, remove from heat and serve immediately.