Tuna Rigatoni

finely slice the onion, simmer the onion slices in melt butter for 5 mins in the pan

meanwhile, heat the water to boil, season with salt, cook the rigatoni according to the package instruction

dice the tomato and pick off the rosemary, stir fry with the onions in the pan, simmer with lid on

drain the oil from the tuna, add them into the the pan

drain the Rigatoni when done, put into the pan, toss together

shred Parmesan cheese over the pan, toss again

season with salt and pepper, and lemon juice

put on a plate, decorate with rosemary, more cheese shred and a good splash of extra virgin olive oil