Set charcoal briquettes in the bottom of the tandoor oven. Light the briquettes with a long fireplace match. Wait for the briquettes to turn white, about 20 to 30 minutes.
Set four small flat pebbles on the lip of the tandoor oven, evenly spaced. Set the flat-bottomed cooking pot on top of the pebbles.
Check that there is 1 to 2 inches of space between the bottom of the pot and the opening of the tandoor oven. This provides ventilation for the briquettes inside the oven and prevents the pot from becoming too hot.
Allow the food to cook inside the pot, stirring occasionally. Lift the pot off the pebbles when the food is ready.
Allow the coals to burn out completely before emptying the tandoor oven chamber