Put the chopped garlic and fresh ginger with 2 tblsp water in a blender and blend to a paste. Chip the potatoes around 15 mm and fry them in 6 tblsp hot oil until all sides are brown (but not cooked through). Remove with a slotted spoon and set aside.
Add the chopped onions to the oil and fry until a golden brown (about 5 minutes). Add the garlic/ginger paste and stir fry for a minute and then put in the ground chili powder, ground coriander seeds and the flour. Stir for another minute then put in 1 tblsp of the yoghurt, and stir for 30 seconds. Add 3 more tblsp yoghurt in the same way stirring for 30 seconds after each tblsp.
Then add the chopped tomatoes and stir fry for 2 minutes. Add 275 ml water and the salt, bring to the boil, then cover and simmer for 10 minutes. Put the fried potatoes and chopped long beans into the sauce, cover and simmer for a further 10 minutes.
Add the garam masala and fresh chopped coriander leaf and mix in gently. Cut the hard boiled eggs in half lengthwise and place them, cut side up, into the sauce.
Spoon a little sauce over them and simmer for 5 more minutes, covered.