Heat oven to 200/180c fan/gas6. Place each Sea Bass fillet, skin side down, on individual squares of foil. Mix together the orange zest, honey, mustard, 1 tbsp olive oil and some seasoning, and drizzle over the fillets. Pull the sides of the foil up and twist the edges together to make individual parcels. Place the parcels on a baking tray and bake in the oven for 10 minutes until the fish is just cooked and flakes easily when pressed with a knife.
Warm the lentils following pack instructions, then mix with the orange juice, remaining oil, the watercress, herbs and seasoning. Divide the lentils between two plates and top each with a sea bass fillet. Drizzle over any roasting juices that are caught in the foil and serve immediately.