Preheat your oven to 300F
Season short ribs with the salt and pepper on all sides
Add the olive oil to a large dutch oven or braiser. Heat on medium high heat.
Sear all sides of the short ribs in batches. This should take about 10 minutes. Once they are all seared, remove them from the pot and set them aside on a plate.
Add the onion, carrot, celery, and garlic to the dutch oven. Reduce heat to medium and let them cook until they start to brown.
Then, add your brown sugar and tomato paste. Give it a good stir and add your broth and beer.
Bring the pot to a boil, and then your short ribs back to the pot.
Add some fresh thyme and a bay leaf, cover the pot, and then bake for 3 - 3 1/2 hours. I flipped my short ribs half way through the cooking process so that I could ensure both sides being fully submerged in liquid for some of the cooking time.