Place a pan over medium high heat and add one tsp of olive oil. Pat dry the cod fillets, season with salt and pepper and add to the pan. Cook for 2-3 minutes on each side, while basting with butter.
Remove the fish from the pan and reserve the hot butter & olive oil mix.
Heat one tsp of olive oil in a saucepan and add the chopped vegetables. Season with salt and cook until soft.
Add the cooked lentils, top with 100ml water and continue cooking for 5-10 minutes.
To serve, place half of the lentil mix on each plate, add the cod fillet and slices of Iberian Ham. Season with lemon juice and drizzle over some of the remaining butter & olive oil mix.