In a large clay pot, pour the rock salt in the bottom and line with banana leaf. Set aside.
Clean the chicken thoroughly inside and out. Drain afterwards for a few minutes.
Then rub with a patis and pepper inside and out thoroughly.
Peel the onion and slice into quarters. Wash the lemon grass and cut the root and weed out the dried leaves.
Pound it using the blunt edge of the knife and tie the whole bunch into a knot so the leaves won't scatter.
Stuff the chicken cavity with crushed garlic, sliced onion and lemon grass.
Arrange the chicken into the claypot in a sitting position with the opening of the cavity facing down so that the heat will penetrate inside the chicken cavity.
Cover tightly as much as possible and cook over a slow fire for about 2 hours until the chicken is cooked and tender.
You can also use stainless steel pot or a pressure cooker.
The cooking time using a stainless steel pot is 1 hour while pressure cooker is only 30 minutes.
Please take care not to let the chicken touch the sides of the metal pot.