Heat a soup pot over medium-high. Add the oil, onion, sweet potatoes, salt, and thyme. Saute until the onion softens, and the sweet potatoes start to carmelize -- about 5 minutes. The bottom of the pan may stick a bit. That's ok.
1 tablespoon olive oil, 1 sweet onion, 3-4 sweet potatoes, pinch of salt, 1 teaspoon dried thyme