Add the lentils, onion, 2 tablespoons of olive oil and all the remaining ingredients to a bowl. Blitz briefly with a hand blender, or mix well with a fork. The mixture should be well mixed with the lentils slightly broken down, but don't over blend so it becomes a mush. You could also use a food processor, but pulse gently and take care not to over process.
2 tbsp ground almonds, 4 tbsp oats, ground to a coarse flour, 2 eggs, 1 tbsp Worcestershire sauce, ¼ tsp mustard powder, salt and pepper, 1 tsp dried mixed herbs