Add your homemade suet, plain flour, baking powder and chopped parsley to a bowl, begin to add the water a table spoon at a time and using a fork stir the mixture slowly bringing the ingredients together.
Continue to add the water (you may not need the full 100ml) until you have a manageable dough with which you can roll into 8 balls.
If not adding to a stew immediately place on a plate and cover with a damp cloth, tea towel or kitchen roll to prevent drying out and cracking.
Add the dumplings to the last 25 minutes of cooking your stew. If you'd rather you can brown them off by removing the casserole lid for the last 5-10 minutes but this may dry out your dumplings
Notes
Let me know how you get on if you try this yourself, I'd love to hear.