Cook the lentils in a pan of boiling water for 20-25 mins or until just done. Meanwhile, squeeze the juice from one lemon into a bowl. Add the onion and scrunch together with a pinch of salt to pickle slightly. Set aside.
Finely zest the remaining lemon and set aside for the halloumi. Squeeze the juice into a jam jar or jug. Add the oil with a pinch of seasoning and the capers – shake well and set aside. When the lentils are ready, drain and tip into a large serving bowl with the chickpeas. Toss with the dressing straight away, then toss through the beets, parsley, pickled onions and their juice.
Heat a frying pan over a medium heat and fry the halloumi for 1-2 mins each side or until golden brown. Toss with the lemon zest, then place on top of your salad to serve.