First things first, preheat your oven to 400°F (200°C). While it heats up, grab a baking dish big enough to hold your flounder fillets in a single layer. For super easy cleanup, you can line it with parchment paper – trust me on this one!
Next, take your beautiful flounder fillets and gently pat them really dry with paper towels. This helps them cook up nicely and not steam.
Now, let's make our magic sauce! In a small bowl, whisk together the melted unsalted butter, olive oil, and fresh lemon juice.
In a separate small bowl (or you can just sprinkle directly if you're careful), mix together the smoked paprika, garlic powder, sea salt, and black pepper. Give it a little stir.
Place your patted-dry flounder fillets in the prepared baking dish.
Brush or drizzle the butter and oil mixture evenly over the fish fillets.
Now, sprinkle the spice mixture evenly over each fillet. Make sure they get a nice coating!
Pop the dish into your preheated oven. Bake for about 12-15 minutes, depending on the thickness of your fillets. Flounder is thin, so it cooks fast! You'll know it's done when the fish is opaque throughout and flakes easily with a fork.
Carefully remove from the oven and serve immediately. That's it! See? Told you it was easy!