Put the refried beans into a large bowl along with the onion, flour, chana masala, and salt and mix well with your hands. Divide and form the mixture into 4 equal-size patties. Heat a nonstick skillet over medium-high heat and add the oil. Place the patties in the pan and fry until they are golden brown on all sides, about 4 to 5 minutes, turning. Serve the burgers on whole wheat buns with desired toppings.
To make the Channa Masala: Blend the mango powder, pomegranate powder, fenugreek leaves, garam masala, turmeric, red chile powder, and salt and store in an air-tight jar for up to 3 months.