Preheat the oven to 180 degrees Celsius.
Wipe the fish with a damp cloth, make a few incisions across the thickest part of the fillets and brush with olive oil and lemon juice.
Heat the olive oil until hot but not smoking and add the capers and sage leaves. Cook until they're crispy. Remove from the oil and lay them out on absorbent paper towel to drain them of excess oil. Heat a grill pan and sear the fish for 2 minutes each side, then transfer the fish to a baking tray and cook for 15 - 20 minutes to cook through.
While the fish is cooking, heat the lentils in a pan and stir through the preserved limes and capsicum.
When the fish is cooked, sprinkle the capers and sage through the lentils. Serve the fish on top of the lentils with an accompanying green salad.
Note: Using canned legumes and pulses are an easy way to incorporate this healthy food group into the daily diet. Always rinse them thoroughly to remove the extra salt.