Heat oven to 200C/180C fan/gas 6.
Pierce the potato skins and place on a
baking tray. Bake for 45 mins until really
soft. Remove from the oven and leave to
cool. Meanwhile, heat the oil in a small
pan, add the onions and chillies, and cook
for 8-10 mins until soft. Leave to cool.
Peel the potatoes and add the flesh to a
bowl with the chilli onions. Mash together
with the spices until smooth. Using your
hands, mix in the sweetcorn, coriander,
half the polenta and some seasoning.
Shape the mixture into 10 burgers; it will
be quite soft. Carefully dip each one into
the remaining polenta; dust off any
excess. Place burgers on oiled baking
trays and chill for at least 30 mins. You can
wrap and freeze the burgers at this stage.
Light the barbecue. When the flames
have died down, place a large, well-oiled
non-stick frying pan or sturdy baking tray
on top of the bars. Cook the burgers in
the pan or on the tray for 10 mins each
side until nicely browned. Alternatively,
heat oven to 220C/200C fan/gas 7 and
cook on oiled baking trays for 15 mins.
Serve in buns with a dollop of salsa,
some onion and salad leaves.