1 cup of table sugar
1/4 cup of water
1/2 tsp DAP yeast nutrient
1/4 tsp cooking lime
Just heat it up, add a dash of cold water if it's boiling too much and colouring too quickly and let it get to the flavour/colour you're after. We found that it turned pretty quickly from amber to black so watch out for that.
It took a few goes to get right but we eventually got it right.