Each serving of this delicious meal provides one vegetable serving.
Place tomatoes, cucumbers, parsley, basil and onions in a large bowl. Combine the oil, lemon juice and garlic and pour over vegetables. Mix well and set aside to marinate.
Place spaghetti squash in boiling water and cook 15 minutes. Prick in four places with a fork and continue cooking another 30 minutes.
Remove squash. Let cool for 5 minutes, then cut in half lengthwise and scoop out seeds. Using a fork, pull out the strands of "spaghetti".
Mix with the well-marinated vegetables. Season with salt and pepper.