Slice bell peppers and onions into thin strips
Heat a skillet over medium-high heat
Add oil to the skillet
Add onions first and cook for 2 to 3 minutes
Add bell peppers and cook for 4 to 6 minutes
Stir occasionally until vegetables are tender-crisp
Season with salt, pepper, garlic powder, and chili powder
Add cumin or smoked paprika if desired
Cook for 1 more minute after seasoning
Remove from heat and serve immediately