Preheat oven 160c/140c Fan/Gas 3. These burgers need to be cooked low and slow.
Using a food processor throw in pumpkin puree, chilli powder, garlic cloves, mustard powder, onion, cumin, salt, oats, and 70% of the black beans. Blend together until you have a paste type mixture.
Fold in the remaining black beans with a wooden spoon.
Form the mixture into four large burger type patties. The mixture will be soft, so use wet hands it will help to keep the mixture from sticking while you form the burgers.
Place baking paper or grease a baking tray. Place the bugers onto the tray and into the oven for 40 - 45 minutes. Turning half way. Cook until Golden brown or until the burgers start to crack.