Heat a large heavy skillet over medium high heat.
Add olive oil, onion and garlic, stirring for 30-60 seconds, then add green beans. Cook stirring occasionally for 1 minute, then add remaining vegetables. Continue cooking 2-3 minutes.
Sprinkle with Thyme, salt and pepper.
Continue cooking an additional 1-2 minutes.
Do not overcook, the squash should retain it's form and not be mushy.