Heat the oil in a large frying pan or wok over medium heat until it is nearly smoking. Be very careful not to leave the pan unattended.
Put the spaghetti in boiling salted water to cook according to package directions.This normally takes about 10 minutes.
When the oil is hot, add the leeks and stir fry until they begin to soften.
Add the red pepper and garlic.
Stir fry for about 3 to 4 minutes, or until the vegetables are soft, but still crisp.
If things seem to be cooking too fast, turn the heat back a bit.
Add the shrimp, and cook, stirring constantly, until they turn pink and are cooked through.
This will take about four minutes.
Reduce the heat and add the tomato sauce.
Heat through and season with salt and pepper to taste.
Drain the spaghetti and divide between two plates.
Serve the Shrimp Primavera over top of the pasta.