Toss the shanks in the flour in a large plastic bag. Shake off any excess flour. Discard excess flour.
Choose SAUTE function and heat half the oil and brown two shanks at a time, remove browned four shanks and set aside.
Add the remaining oil and the onion, carrots and garlic into the inner pot. Fry for 5 minutes, stir occasionally.
Add the tomatoes, oregano, lemon rind, wine and stock. Bring to the boil, stir well, for a few minutes.
Spoon out some of the sauce and vegetables and return the lamb shanks to the inner pot. Return those sauce and vegetables over the shanks in the inner pot.
Close the lid and set the pressure release valve to closed.
Choose MEAT function and adjust the timer between 25 and 30 minutes (depends on how tender you want the meat to be)
When the cooking finished, carefully quick release pressure and open the lid. Remove the vegetables and shanks, set aside. Leave the gravy in the pot.
Add the remaining flour to the cold water and stir until smooth.
Choose BOIL function and set the temperature at 95°C to simmer the gravy and add the flour paste in slowly until the gravy thickens.