In a frying pan, saute the chopped onion until transparent.
Put the oats, sunflower seeds, garlic and the fried onion in a food processor. Pulse until oats are looking very finely chopped with some ground bits. Do not ground the oats completely, we need leave some texture! Transfer the mixture in a mixing bowl.
Preheat the oven to 177°C (gas mark 4). Prepare a baking tray lined with a baking sheet and spread some oil to grease.
Add the dry herb, tomato puree, soy sauce, margarine, the chickpea flour, salt and black pepper into the oats mixture and mix until combined with your hand. The consistency should be firm so that you can form the sausage shape easily. If it's too soft add some more chickpea flour.
Form the sausage shape. You should be able to make 9 or 10 sausages, although if you make it bigger like hot dog sausage you will make less.
Place the sausages on the prepared baking tray. Bake for about 20 minutes or until nicely browned on both sides. Do not forget to flip over halfway through cooking.