You will need (and I'm not going to give you firm quantities because you can do whatever you like):-
Other stuff you have to hand.
First of all, pour yourself a glass of wine, I am convinced that it helps the cooking process.
Then chop up a small onion, stick this in a saucepan with some olive oil and gently fry it. When the onion is cooked, add a couple of finely chopped tomatoes. At this point start your tagliatelli cooking in another pan. Now, to the first pan, you can add anything else you have around, perhaps half a chopped pepper, or some sweet corn, or some cannelli beans, a couple of finely chopped mushrooms, whatever. I really like this with some pine nuts thrown in, but you could use chopped olives.
When the sauce is cooked through your tagliatelli should just about be done as well. Strain the pasta and, taking the first pan off the heat, add it to the sauce and mix it in so that it is coated with the sauce. Now add some salad leaves, again whatever you have to hand - it doesn't really matter. The idea is that the salad leaves should be wilted rather than cooked, a sort of warm salad. Spinach leaves would be good too and basil leaves, especially good. Finally squeeze the juice of half a lime over the pasta, salad and sauce mix and serve.
If you are cooking this for more than one person just increase the quantities appropriately.