Heat a large frying pan over high heat. Add 2 tablespoons oil and mushrooms, cook, shaking pan often 3 minutes until mushrooms start to colour. Remove to a plate.
Reduce heat to medium, add remaining oil and the onion, cook stirring 4 minutes until soft. Add garlic, paprika and chilli flakes, cook stirring 1 minute. Return the mushrooms. Add the tomatoes and bring to the boil. Simmer gently 10 minutes. Add lentils, olives and lemon rind. Simmer 5 minutes. Squeeze over the juice from 1 lemon quarter. Season with pepper.
Remove from the heat, crumble over the feta, sprinkle with parsley. Serve with yoghurt, bread and remaining lemon wedges.
Tip for a non-vegetarian option; Cut 4 chicken thigh fillets in half crossways and brown after step 1 above. Remove to a plate. Follow step 2, returning the chicken to the pan with the mushrooms.