Drain potatoes and put in a bowl. Add paprika powder, red chilli powder, black pepper powder, Lebanese spice powder, coriander powder and salt and mix well. Set aside.
Heat oil in a non-stick pan. Add garlic and sauté till well-browned.
Add potatoes, mix well, cover and cook on low heat for 2 minutes. Sprinkle little water, mix well, cover and cook till half done.
Add tomato ketchup, mix well, sprinkle some more water, mix again, cover and cook for 2-3 minutes.
Add sumac powder, coriander leaves and mix well. Switch off heat.