ok so im a crap cook and unimaginative with food. i love to eat it but cant be arsed to make it. if tea was up to me then id just have a sandwich every night so there were no dishes to wash.
however im on maternity leave and due back at work soon and want to change my eating ways! i dont mind eating something that i like everyday and until recently had buttery toast for breakfast and lunch every day. now i have porridge for breakfast hurrah 
but what to do about lunch! i really dont want to just take butties into work every day!
could anyone please suggest just one recipe that they know which is:
basic or few ingredients;
healthy (not sure i include pasta with that);
filling;
can be made night before or even several days before and served hot or cold:
TASTY 
thanks in advance. i find lunch the hardest habit to change. it really shouldnt be about fannying about in the kitchen for ages for a 2 minute chomp. please help 