Preheat the oven 190°C. Cut the red pepper into chunks and the onion into thin wedges. Arrange them on a baking tray, add the oil and oregano. Season to taste, then toss well. Bake in the oven for about 30 minutes, until the veggies are tender.
Put some vegan and/or normal sausages on another tray and put this in the oven too, until they are brown.
Meanwhile, put the lentils in a pan of cold water, add the garlic and bay leaf and bring to the boil. Cook for 15-20 minutes or until tender. Drain, then remove the bay leaf and transfer the lentils and garlic to a mixing bowl.
Add the oil, mustard, parsley, minced garlic and lemon juice. Season to taste. Add a drop of cider vinegar. Toss well.
Discard the skins of the roasted vegetables and cut them into thin slices. Add these to the lentils, together with any cooking jus. Toss again.
Cut the sausage into chunks, then serve on top of the lentils.