Begin by blitzing all of the dough ingredients in a food processor for about 1 minute, or until the dough begins to hold together as one mass. Using a food processor ensures that the charcoal colour is maximised, but this step can also be completed by hand.
On a lightly floured surface, knead the dough by hand for 10 minutes. If it sticks to your hands or the kneading surface, add flour at a rate of no more than 1 tablespoon at a time, and combine thoroughly.
Transfer to an airtight container and rest for 30 minutes, out of direct sunlight and heat.
To prepare the filling, slice the onion and add into a cold pan with 2 tablespoons of olive oil, and the chilli flakes. Bring up to low-medium heat, and cook gently for 30-40 minutes until they begin to caramelise. To assist the process, add 1/4 cup of water part way through, and allow it to reduce back down.
Once the onions are soft and translucent, add a dash of balsamic vinegar, and cook for a further 5 minutes, stirring. Remove from the heat and set aside.
Next, toss the capsicums in 1 tablespoon of olive oil, and roast in a 200 degree Celsius oven for 20 minutes, or until they start to char. Remove from oven, setting aside the capsicums and retaining the leftover oil.
Once the capsicums have cooled enough to handle, break them open and drain the water that will have accumulated into the retained oil. Set this liquid aside for plating.
Using a food processor, blend the meat, capsicums, caramelised onion, and parsley into a rough paste. Load this into a piping bag with a medium round tip to prepare for filling the pasta. Alternatively, you can use a teaspoon.
Returning to the dough, cut it in half and seal the half not currently being worked on back in the airtight container.
Using a pasta machine, roll the dough through on the thickest setting 2-3 times, folding over itself in between passes. Then step up incrementally to a thickness of 6.
Use a rolling pasta cutter or knife to cut squares of about 95-100mm. Collect the offcuts and store in the airtight container. These can later be recombined by kneading together and repeating the previous step.
Roll the filling into little grape sized balls and place one into the centre of each square. To shape the pasta, gather the edges together so that the filling forms a ball and the outer edges ruffle above it. It should look like a small money bag. Ensure that no air is trapped inside, and that the filling does not squeeze out as you apply pressure around the centre to seal.
Transfer to baking paper lined trays, and refrigerate uncovered for up to a day. Alternatively, freeze in an airtight container.
To prepare the sauce, stir the garlic through the yoghurt and season to taste with salt and pepper.
Plate the dish by dolloping the yoghurt sauce on to the plate, creating hollows with the back of the spoon. Use a teaspoon to fill with the infused oil. Arrange the sacchettoni on top, sprinkle with sumac, and serve.