Saute onions in 1/4 cup water over high heat until translucent. Add garlic, ginger & spices and saute 2 minutes more, adding more water if necessary to prevent sticking or burning. Add spinach, 1 cup water and salt to taste. Reduce heat to low and simmer 10-15 minutes, or until the spinach is dark green and wilting. Remove from heat and allow to cool a little. Use a blender or processor to lightly puree greens. Stir in optional garam masala and serve.