I know I should be insisting that there is nothing to beat fresh peas, but, honestly, for this recipe I think frozen petits pois are better – not least because, cooked like this, they taste remarkably like young, fresh peas. You can use some of the outer lettuce leaves you would normally discard, but not if they are very tough/damaged/grimy. The number of leaves depends on the variety/size.
40g butter, cut into about eight pieces, plus extra for greasing
10-20 firm, crisp lettuce leaves (eg cos or outer little gem), washed and drained but not dried
850g frozen petits pois
3 sprigs of mint
½ tsp caster sugar
Lightly butter a heavy-based casserole or saucepan (lid included), into which the peas will fit quite neatly.
Line the bottom and sides with lettuce leaves. Tip in the frozen petit pois. Add the mint, pushing it down into the peas (if they’re not frozen together like an iceberg). Dot with the butter, sprinkle with sugar and salt and cover with the remaining lettuce leaves.
Cover the pan tightly and cook on a gentle heat for 25 minutes, shaking the pan occasionally (lid held down firmly). Remove the mint, stir in the lettuce leaves and serve.