Hi Mark
Dl is short for a deci-litre
or 1/10th of a litre or 100 ml
of course depends on which coriander seeds you are using
as some seeds are larger than others.
The ones the Hari Kristnas use are the larger variety
I forgot to say that you should roast and grind them the
usual way, you will end up with a very nice smelling
masala which works much better than Kris Dhillions own
garam masala recipe, IMO.
The tip here is to be very careful with the fenugreek seeds
as they become bitter if they burn, they recommend only
4-5 minutes roasting, i use preground fenugreek
as it works in most dishes. As spices become most
aromatic at different times i like to roast them individually
in a khari on a medium heat and check for colour and
smell to get the optimum flavour. Its worth the effort i think.