In a large pot, put baby back ribs, peppercorns, lemongrass, galangal and kaffir lime leaves. Fill water to cover the ribs and bring to boil. Lower the heat and let the mixture simmer for 1 and a half hour.
When the ribs are cooked through and soft, transfer the ribs to flat tray and quickly cool the temperature down and then nicely trim edges and individually cut apart.
In mortar, pound garlic, coriander root and black peppercorn with pestle until paste forms. Rub the paste over the ribs and marinate overnight.
Bring tamarind paste, palm sugar and oyster sauce to boil. Reduce the sauce until thick.
Dip the cut ribs in tamarind sauce and arrange on a baking tray. Place under broiler for 5 minutes until slightly charred. Transfer to a warm plate, garnish with coriander and serve.
Recipe contributed as part of the Senses of Thailand promotion at Selfridges.