Mix au jus gravy mix, flour, thyme and brown sugar in a small bowl, making sure to get any lumps out of the brown sugar. Place into a 4-6 quart slow cooker. FYI–I used a 3.5 quart casserole crock to make this. Add the ale and stir well to combine.
Heat a heavy skillet over medium-high heat. Add the oil and brown short ribs on all sides. Remove to a plate.
In the same pan, saute the sliced onion and garlic, stirring constantly, for about 3-5 minutes–don’t let it burn.
Deglaze the pan with the 1/2 cup water; mix the onions and water into the au jus mixture in the slow cooker.
Place the short ribs in the slow cooker, cover and cook on HI 4-6 hours or LOW 8-10 hours (times are approximate). If using the casserole crock, please read the above post–it will probably take longer in one of those.
Remove the ribs to a serving plate. Stir in the heavy cream, combining well. Pour gravy over short ribs.
Serves about 4 people (I had 8 short ribs and allowed 2 meaty ribs per person).