Step 1 Peel wide, flat ribbons from zucchini with a vegetable peeler. Place a non-stick grill pan over medium heat or heat a barbecue hotplate to high. Spray zucchini ribbons with olive oil and cook for 1–2 minutes, or until just tender. Use tongs to remove each ribbon carefully from pan; set aside.
Step 2 Steam or microwave asparagus spears for 2–3 minutes, or until just tender, then immerse in cold water. Place cool spears on paper towel to drain well; set aside.
Step 3 Meanwhile, combine ricotta, feta, dill (or parsley), lemon zest and nutmeg in a mixing bowl (or blend in a food processor).
Step 4 Line a 750ml-capacity terrine mould with a large sheet of cling film. Line inside of terrine mould with three-quarters of the reserved zucchini, overlapping ribbons to cover base and sides of mould.
Step 5 Top zucchini in mould base with half of the ricotta mixture, then press half of the asparagus into mixture, spears running parallel. Spread asparagus with remaining ricotta mixture; press in remaining spears. Fold overhanging zucchini ribbons over asparagus and press any leftover zucchini ribbons into ricotta mixture to fill any gaps.
Step 6 Wrap terrine in cling film to seal, top with a light weight (such as a packet of rice) and place in fridge to chill for at least 2 hours.
Step 7 Cut terrine carefully into slices and serve with dark rye bread.