Lay the chicken breast fillets on a large sheet of cling film, well spaced out. Lay another piece of cling film on top and bang with a rolling pin until the chicken has flattened out. Put the lemon juice in a bowl and stir in the spices and a little freshly ground black pepper. Lift off the top layer of cling film and spread the spiced lemon juice over the chicken. Lay the cling film loosely over the top again and leave for half an hour. Meanwhile, cut the peppers in half, discard the seeds and stem and put the halves, skin-side up, under a hot grill until blackened all over. Wrap in a plastic bag or tin foil until cool, then peel off the skin, slice the peppers across very thinly and put into a mixing bowl.
Put the mushrooms in a food processor, whizz to chop finely, then add them to the peppers. Cut the chillies open lengthways under running water, discard the seeds and stems and chop finely. Peel the garlic and ginger and chop finely. Add these ingredients to the bowl and season with salt. Whisk the eggs lightly and stir into the mixture.
Preheat the oven to 190°C/375°F/gas mark 5. Remove the stalks from the spinach and chop the leaves as finely as possible. Spread the chopped spinach evenly on top of each chicken breast fillet, patting it down. Then spread the pepper and mushroom mixture on top of the spinach. Roll up each chicken fillet, enclosing the stuffing. Don’t worry if they fall apart a bit; just press together. Wrap each fillet in a fairly large piece of oiled foil to enclose completely, then wrap in a second piece of foil.
Put the bundles in a roasting pan and cook in the oven for 40-45 minutes. Leave to cool and then chill in the fridge, still wrapped up. To serve, unwrap the chilled bundles and cut across into slices 1.25cm/½in thick. Arrange salad leaves on large serving plates with the chicken slices on top and scatter with coriander leaves.