Cook the potatoes whole in their skins in a pot of lightly salted, boiling water for about 15 minutes until tender.
Meanwhile, mix together all the ingredients for the dressing and cut the beets into thin julienne strips about 3 cm long. Cook the peas for 2-3 minutes in a dish in the microwave or in the pot of boiling water with the potatoes until tender, then drain well.
Drain the potatoes and thickly slice, then put them in a large serving bowl with the peas, half the scallions and the pastrami, loosely folded.
Just before serving, very lightly stir the beets into the salad and drizzle with the dressing. Scatter the remaining scallions and the radishes over the top. Serve warm.
Variations: For vegetarians, omit the pastrami and add 2-3 hard-boiled eggs,cut into quarters, to the salad just before adding the salad dressing. For a different flavour, swap the pastrami for 200 grams (7 oz) of herring fillets in tomato sauce, you may like to cut the herrings into strips to make them easier to eat.
Each serving: 12.5 g protein, 2.5 g fat of which 0.5 g saturates, 35 g carbohydrate, 8 g fibre, 231 Calories