In a mortar & pestle, break up the whole spices into smaller pieces with a few good strikes.

Transfer the spices to a dry, heavy skillet and toast over medium-high heat, shaking the pan occasionally, until the spices are fragrant and just beginning to smoke. Watch the pan carefully, this should only take a few minutes. 

Transfer the spices to your slow cooker. Coat the ribs with one tablespoon of vegetable oil and sprinkle with kosher salt.

Add the remaining oil to a heavy skillet and preheat to medium-high. Working in batches so as not to crowd the pan, sear the ribs until they are browned on all sides, about 2 minutes per side and transfer them to the slow cooker. 

Add the onion and beer and water or stock to the slow cooker.

Cook on low for 8 hours or high for 6 hours, until the meat falls off the bone. Remove the meat from the slow cooker and strain the juices through a sieve. Skim the fat from the juices and remove the meat from the bones. Return the meat and juices to the slow cooker or a dutch oven on the stove top and warm them together.

Serve the meat on rolls with crispy vegetables, bahn mi-style or with rice or potatoes for a heartier meal.