Step 1

Preheat oven to 200°C/400°F.

Step 2

Place potato on a baking-paper-lined oven tray; spray potato with oil, season. Roast, uncovered, for 30 minutes.

Step 3

Cut fish into quarters, place on top of potatoes; roast, uncovered, for about 15 minutes or until potato is browned lightly and tender and salmon is cooked as desired.

Step 4

Meanwhile, combine buttermilk, juice, mustard, anchovy, gherkin, parsley and garlic in a small bowl; season to taste.

Step 5

Boil, steam or microwave asparagus, snow peas and beans separately until tender; drain. Rinse under cold water; drain.

Step 6

Combine watercress, potato, asparagus, snow peas, beans and fish on serving plates; drizzle with buttermilk dressing.