Slice the bell peppers and onion into thin, evenly sized strips so they cook at approximately the same rate.
Place a large skillet over medium-high heat and allow the cooking surface to become very hot.
Add the olive oil, followed immediately by the sliced peppers and onions.
Cook for about 4 minutes without stirring too frequently, allowing some browned edges to develop.
Add the oregano, salt, and black pepper, then continue cooking for another 3 to 4 minutes.
Remove the vegetables while still slightly crisp, stir in the optional lime juice, and serve immediately.