Cover bottom of a large skillet with the olive oil.
Turn heat to high and brown the onion, garlic and squash just a little bit.
While you are browning the vegetables, sprinkle them with basil.
When the vegetables are slightly browned, remove from heat.If you use fresh tomatoes, cook them in a non-stick frying pan on medium heat for about five minutes to let the juices from the tomato evaporate a little.
After five minutes, add the tomatoes to the other vegetables and stir.
If using canned diced tomatoes, they can be added directly to the other vegetables.
Salt and Pepper to taste.
Let simmer on low until the squash is tender.