Ingredients
150g penne 
1 tin of tuna (these are around 145/160g) 
8-10 tbsps mayonnaise 
½ a red onion very finely chopped (optional) 
1 small orange or red pepper cut very small (optional) 
1 small 198g tin of sweetcorn (or 165g frozen corn) 
Salt 
Freshly ground black pepper 

Method
Get a large pot of heavily salted water on to boil and when at a rolling boil put your pasta in, stir and cook according to the packet instructions. 

Meanwhile mix the tuna, mayo, pepper and a little seasoning to taste.  Start with 6 tbsps of mayo and increase if needed remembering that your mixture needs to have be wetter than you would have for sandwiches as it needs to be able to coat the pasta. 

When your pasta is cooked, drain well and put back into the saucepan.  If you are using red onion mix this through the pasta while the pasta is warm and add 2 tbsps of mayonnaise and thoroughly mix.  Add the tuna mix and sweetcorn and thoroughly but carefully mix through.  Check the seasoning and grind over the black pepper.