Preheat the oven to 180ºC with air or 200ºC with heat up and down. Peel and cut the pumpkin or gourds into pieces approximately 1 cm thick, discarding the seeds. Place on one or two baking trays (with aluminum foil or sulphurised, if you prefer), season and add a few 20-30 ml of the indicated oil, stirring everything well.
Bake for 25 minutes; turn the pieces carefully or stir and bake for another 15-20 minutes, until lightly caramelized and slightly toasted. Watch before in case the smaller pieces start to scorch.
While the pumpkin is baking, mash the peeled garlic with a pinch of salt using a knife or mortar. until you get a paste. Use only one if you prefer softer, or remove the germ. Put in a bowl with the chili or paprika and the sumac, if using.
Wash and dry the parsley and lemon well. Chop the leaves and the finest stems with a knife until they are 1.5 cups of minced herb. Also chop the pistachios, leaving irregular pieces. Add to the bowl with the squeezed lemon juice, the vinegar and almost all the oil. Stir, taste and adjust for salt, vinegar or oil.
Serve the pumpkin in a bowl spreading the gremolata and the pomegranate grains on top. Take the leftover gremolata to a bowl for each diner to serve, or store in an airtight container in the fridge.