In a hot, large (and fairly deep) braising pan, sear the seasoned beef on both sides to brown in as little oil as possible oil. Short Ribs are fatty so not much will be needed.
Add onions, garlic, celery, carrots, bay leaf and thyme and cook until translucent. Dust ingredients with corn starch, just enough to absorb oil and lightly coat. (This will be used to thicken.)
Add Zinfandel and simmer to reduce by half.
Add broth and tomato paste, stir and continue to simmer until beef can be pierced easily. (A good indicator of tenderness is by using a dinner knife or a spoon to pierce.) This will usually be about one and a half to two hours. Add liquid as needed. When ready, skim out beef and strain sauce. Return sauce to braising pan, add the root veggies and cook until al dente. Add beef back to pan to reheat.