Season short ribs generously with salt and pepper on all sides. Set aside.

Select the brown/ sauté mode on your slow cooker. Set the temperature to 400F degrees. Add oil, when oil is very hot add in beef short ribs (see notes)

Brown beef on all sides. Work in batches if you need to but do not overcrowd the slow cooker (about 15 minutes). Transfer beef short ribs to a plate.

Using the oil and browned bits that are left in the slow cooker, sauté the onions, garlic, carrots, and celery until softened (about 5-6 minutes).

Stir in red wine vinegar, coconut aminos (or soy) and bourbon. Let the liquid reduce by half (about 3 minutes)

Whisk in the tomato paste and four until mixture has thickened (about 1 minute).

Stir in the broth and whisk to combine. Turn off sauté mode.

Transfer beef back to the slow cooker. Top with fresh thyme. Cover and cook on high for 4 hours or low for 6 hours.