Brown onion sauce

2 onions, chopped
1 teaspoon tamarind paste (from 1 inch cube of dry tamarind)
1 tablespoon marmite
soy sauce
black pepper

Cook the onions slowly in a dutch oven over low heat, stirring regularly, for 45 minutes until they are much reduced and rich brown. Meanwhile, steep the dry tamarind in hot water for a few minutes and then pass it through a sieve to make the paste. Thin out the marmite with some hot water. Mix in the tamarind, soy sauce and black pepper. When the onions are done, blitz them together with the marmite liquid.