Place red wine, port, thyme, garlic, bay leaf and peppercorns into a medium sized heavy based saucepan and bring to the boil over a high heat.
Boil vigorously to reduce alcohol to 100ml, for 10-15 minutes.⏱ 15 min
Add veal glace, reduce heat to low and simmer for 8 minutes, skimming from time to time.⏱ 8 min
Pass through a fine sieve, taking care not to allow any sediment to pass into the sauce.