Make Spice Paste:

1. Heat a small skillet over medium heat and toast the coriander seeds until fragrant about 2-3 mins. Put them in a spice grinder or mortar and pestle and grind finely.
2. In a food processor or the mortar and pestle (I used an immersion blender), add the ground coriander, the white pepper, black pepper, salt, fish sauce, brown sugar, garlic, oil, turmeric powder, ginger, oyster sauce, and cilantro leaves/roots. Process to create a smooth paste, about 1 min. If using a mortar and pestle, add each ingredient one at a time to make it easier to get a smooth paste. 
3. If you are using coriander roots which are fibrous and tough, first use the side of your kitchen knife to smash them up and then cut them into small pieces before adding to the mortar.
4. Spread the paste evenly over the ribs giving them a little massage. Put the ribs in a flat sheet pan or a plastic container, cover them with plastic wrap, and refrigerate overnight.

Roast the Ribs:

1. Pull the ribs out 1 hour or two before you plan to cook them.  Preheat the oven to 300. Take off the plastic wrap and arrange the ribs so they are in a single layer. Then cover the ribs tightly on the tray with aluminum foil. 
2. Put the ribs in the oven in the middle rack and roast for 3-3 1/2 hours until the ribs are tender. Remove the foil after 2 ½ hours and then continue cooking uncovered for the remaining time.
3. When the ribs are done, you can use a fork to test between the ribs. The fork should slide in without too much resistance. I prefer ribs that do not fall apart because I find the texture nicer but if you like them very soft, plan for a little extra time.
4. Cut in between the bones to create individual ribs, stack them up on a platter, and serve immediately.