2-3 (about 500g) long, slim sweet potatoes
1 large (about 200g) white-skinned potato
1 large (about 200g) red-skinned potato
75g butter in 1cm cubes
6 sprigs fresh thyme, rosemary or savoury
Salt and pepper
75g Cotswold Blue or Blue Vinney or other blue cheese
4x36cm squaresof greaseproof paper or aluminium foil, or 4 medium oven bags
Step 1) Wash and paper-dry the potatoes. Slice the sweet potatoes very thinly crossways. Cut the other potatoes in half lengthways, then slice very thinly crossways. Keep the varieties separate.
Step 2) Take one papillote and rub its centre with a little butter. On it place three rows of slightly stacked potatoes: sweet, white- then red-skinned. Dot with butter. Scatter over whole or chopped herbs, reserving 4 sprigs. Season. Gather up one papillote edge. Roll, twist and crimp the sides together to form a semi-circular purse shape; use heatproof clips or wooden pegs, if necessary. Do not puncture the paper. Repeat for the other 3 parcels and set in a steamer.
Step 3) Cook for 30-35 minutes, if using a tiered steamer, steamer insert or electric steamer; or 8-12 minutes on high in a microwave. Follow manufacturer’s guide if using a steamer oven.
Step 4) After cooking, open parcels, add mascarpone, a cube of blue cheese and a sprig of herb to each. Enjoy !!