Cook the pumpkin in boiling water until almost tender. You should only be able to push a fork in about 1-2 cm, no more.
Remove the pumpkin from boiling water and rinse under cold water so that it is cool enough to hold. Then using a grater, grate the pumpkin into a bowl
Wash all visible dirt from the leek stem, shred it and chop into fine pieces. Add to the bowl of grated pumpkin. Mix with your hands to combine well.
To make the herb oat crumb, combine all the ingredients in a blender and mix until a crumbly consistency is formed.
Add 1-2 tablespoons of the oat herb crumb to the pumpkin and leek mix, and with your hands, mix to combine. You should now be able to form balls of this rosti mix.
Melt margarine in a frying pan, over medium heat.
Form a ball of the rosti mix in your hand, about the size of a tennis ball. Add the ball to the pan and with a spatula, push down on the ball to flatten it to about 1.5cm in height. Repeat until all the rosti mix is used.
Fry the rosti until it is golden on one side, and you can flip it to fry the other side.
Once both sides are golden and cooked through, remove from the pan and serve. We sandwiched together two rosti with a leek and fava bean ‘guacamole’ and topped it with a poached egg, and served alongside a kale salad with some pickled red onions. Delicious!