Shred finely two lettuces into a bowl and incorporate a dressing made by mixing two tablespoonfuls of salad oil and one of vinegar, a dessertspoonful of tarragon vinegar, and a little pepper and salt and a saltspoonful of dissolved mustard. Take a salad bowl, arrange a layer of sliced cooked potatoes at the bottom, followed by a layer of thinly-sliced corned beef; cover the meat with dressed lettuce, and scatter some coarsely-chopped beetroot over the top; then put a second layer of potatoes, beef and lettuce, and garnish with beetroot and hard-boiled eggs cut into slices.