Turn your oven to 250C (480F). Place fish / chicken on a rimmed baking sheet (I line mine with baking paper). Scatter over the frozen veg so everything is in a single layer.
Pop in the oven. Set your timer for 10 minutes.
For the salsa, peel lemon using a knife to cut off the peel. Chop lemon flesh into small dice, discarding any seeds as you go. Chop the herbs. Combine pine nuts, diced lemon, herbs and olive oil in a small bowl. Taste and season with a pinch of salt (or more if needed).
When the timer goes check the fish / chicken is cooked to you liking. Divide protein and veg between two plates and top with the salsa.