Heat oven to 200C/180C fan/gas 6. Mix together 1 tbsp oil, the mustard, honey and some seasoning. Put the salmon fillets on a baking tray and spread the honey and mustard mixture all over. Tip the lentils and beetroot into a casserole dish, toss with the remaining oil and season well. Put both in the oven for 10 mins until the salmon is cooked through.
Stir the crème fraîche, dill, capers and lemon zest through the lentils. Serve alongside the salmon with the pumpkin seeds scattered over and lemon wedges for squeezing, with a rocket salad on the side, if you like.