Trim the steak and cut it across the grain into strips about 1/2 inch thick and 3–4 inches long. Pat the strips dry, then season them with about 1/2 teaspoon kosher salt, the black pepper, and garlic powder.

Prepare three shallow bowls. Put the flour and remaining salt in the first, beat the eggs with the water or milk in the second, and combine the panko, Parmesan, and paprika in the third.

Coat each steak strip in flour, dip it into the egg mixture, and press it firmly into the panko mixture. For a thicker crust, dip the strip in egg and panko a second time.

Refrigerate the coated steak fingers for 10–15 minutes. This short rest helps the breading adhere during frying and gives the coating a better chance to stay attached.

Make the pesto by pulsing basil, pine nuts, garlic, Parmesan, and salt in a food processor. Gradually add the olive oil until the sauce is smooth but still slightly textured, then stir in lemon juice if using.

Heat about 1/4 inch of neutral oil in a heavy skillet to approximately 350°F (175°C). Fry the steak fingers in batches for about 2–3 minutes per side, turning once, until deeply golden and cooked through.

Transfer the cooked steak fingers to a wire rack or paper towels and season lightly with salt. Let thin sirloin strips rest for 3 minutes after reaching at least 145°F (63°C), then serve immediately with pesto for dipping.