Heat olive oil in a large skillet over medium heat.
Add diced sweet potatoes in a single layer and season lightly with salt.
Cook undisturbed for 4–5 minutes to allow browning, then stir.
Continue cooking, stirring occasionally, until sweet potatoes are tender and golden, about 10–12 minutes total.
Add onion and bell pepper if using. Cook until softened, about 4 minutes.
Stir in garlic and paprika and cook for 30 seconds until fragrant.
Season with black pepper and additional salt if needed.
Remove from heat and garnish if desired. Serve hot.