Unwrap the string cheese sticks and set them aside.
Pour oil into a deep frying pan or skillet to about 2 inches deep and heat over medium-high until it reaches 350–360°F (sizzling).
In a shallow bowl, whisk together the buttermilk, egg, 1/4 teaspoon salt, and 1/4 teaspoon black pepper until combined.
In a second shallow bowl, combine the panko breadcrumbs, Italian herbs, smoked paprika, and garlic powder; stir well.
Working one at a time, dip a cheese stick into the buttermilk mixture and let excess drip off, then coat evenly in the breadcrumb mixture, dip quickly again in the buttermilk, and finish with another coating of breadcrumbs to build a thick crust.
Carefully add the coated cheese sticks to the hot oil without crowding the pan; fry about 20–30 seconds per side (about 1 minute total) until the crust is golden brown.
Use a slotted spoon or tongs to transfer fried cheese sticks to paper towels to drain briefly.
Serve immediately with marinara sauce or your preferred dip.