Preheat the oven to 200c / 180c fan / 400f / gas mark 6 and line one or two oven trays.
Add all the prepared vegetables to a large mixing bowl. You can vary the veg depending on what you have.
Give it a good mix, then add the drained lentils.
Next, add the spices and seasoning (salt & pepper), then the tomato puree.
Give it a good mix, then blend half or just under half the mixture in a blender or food processor.
Mix it back into the rest of the veg and lentils still in the bowl.
Add the oats and mix well. That's your filling ready.
Take your pastry out of the packet and gently unroll it (if it's a block, roll it into a large rectangle, fairly thin (about ½ cm). Cut the pastry in half so you have 2 long rectangular pieces.
Spoon a quarter of the pastry along the centre or just off centre of each long piece of pastry in a sausage-shaped pile from end to end.
Rub one long edge of the pastry with a little water, then fold the pastry over the filling and press to seal. Use a fork along the sealed edges, then cut into 6 pieces.
Do this for all 4 rectangles of pastry (2 boxes of ready-rolled puff pastry or 2 blocks) until you have 24 small sausage rolls.
Place each sausage roll on a lined baking sheet (if baking in the oven).
Slit the top of each sausage roll a couple of times, to let out the steam.
Brush each sausage roll with olive oil, the sprinkle over some sesame seeds.
Bake until golden in a pre-heated oven.
Enjoy!