Preheat oven to 180°C/160°C fan-forced. Oil 14cm x 21cm loaf pan.

Cut potatoes into 2mm slices. Add potato to large saucepan of boiling water; cook about 4 minutes or until potatoes are just beginning to soften; drain.

Preheat grill. Quarter capsicum, remove seeds and membranes. Roast under grill, skin-side up, until skin blisters and blackens. Cover capsicum pieces in plastic or paper 5 minutes; peel away skin.

Cut eggplant lengthways into 5mm slices; spray slices, both sides, with oil. Cook eggplant, in large frying pan, until browned both sides; drain on absorbent paper.

Cut white part of leek into 7cm lengths; cut lengths in half. Boil, steam or microwave leek until tender. Drain, rinse under cold water; drain.

Combine oil, garlic, thyme and pepper in small bowl.

Cover base and long sides of pan with prosciutto, allowing prosciutto to overhang edges. Place half of the potato, overlapping, over base, brush with herb oil mixture; top with half of the cheese, brush with herb oil mixture.

Layer capsicum, eggplant, basil and leek, brushing each layer with herb oil mixture. Top leek layer with remaining cheese then remaining potato, brushing with herb oil mixture between layers; press down firmly. Cover terrine with prosciutto slices.

Cover terrine with foil, place on oven tray. Bake 1 hour; uncover, cook further 40 minutes. Remove from oven, pour off any liquid. Cool 5 minutes; cover top of terrine with plastic wrap, weight with two large heavy cans for 1 hour.

Make saffron vinaigrette. Place olive oil, lemon juice and saffron in a screw-top jar; shake well. Serve with sliced terrine.