Step 1

To make mustard dressing, combine olive oil, vinegar, garlic, mustard and sugar in a screw-top jar. Shake well. Season to taste.

Step 2

Scrub potatoes to clean, if necessary. Boil, steam or microwave potatoes until tender, then drain. When cool enough to handle, cut potatoes into thick slices and toss in half of the mustard dressing.

Step 3

Meanwhile, boil, steam or microwave both beans, separately, until just tender. Drain. Rinse under cold water and drain well. Peel away grey skins from broad beans.

Step 4

Place potato on a platter, top with tomato and beans; drizzle with remaining mustard dressing.