Heat oven to 200C/180C fan/gas 6.
Cut the white ends from the spring
onions and slice them in half
lengthways. Finely chop the green
tops. Tip the butter, flour, mustard
and milk into a non-stick pan with
seasoning, and whisk over the heat
until the mixture thickens to make
a sauce. Add the whites of the onion
and cook for a few mins, stirring until
they start to soften. Stir in the
sweetcorn and tuna.
Heat the tortillas following pack
instructions. Divide the mixture
between the tortillas and roll up
like pancakes. Arrange the pancakes
in a large, buttered ovenproof dish
as you roll them. Mix the cheese
with the onion tops, sprinkle over
the pancakes and bake for 25 mins
until bubbling hot.