HP Sauce to the British is like Ketchup to every North American.
It took me years to create this clone, it's original, and it's perfect.
Try it for yourself.
Recipe volume can be increased 4 times without flavour loss.
In a large pot, add water, white vinegar, tomato paste, corn syrup, orange juice concentrate, dates, molasses, apple juice, and tamarind pulp. Stir to blend. Over medium heat and covered, bring mixture to a boil. Reduce heat to a slow simmer and simmer covered for 15 - 20 minutes.
Using a spice grinder, thoroughly grind onion powder, cloves, black peppercorns, cardamom, garlic powder, mustard seed, cayenne, salt, and cinnamon.
After simmering in step #1, use an immersion Blender to purée mixture and reduce lumps. Add ground spice mixture to pot, stir to blend and simmer (covered) for another 30 - 45 minutes.
Add cider vinegar to pot, stir to blend and return to a simmer. When pot has reached a simmer, remove from heat and strain hot mixture through a wire strainer into a clean pot. Keep liquid, discard pulp. Rinse original pot and restrain mixture back into original pot, return to heat and simmer until thick.
Ladle hot sauce mixture into hot, prepared sealable bottles and seal. Allow to cool. Keeps indefinitely in cupboard, refrigerate after opening.