Prepare three shallow bowls: in bowl 1 whisk together 1/2 cup flour and 2 teaspoons of the ranch seasoning; in bowl 2 mix 1/3 cup flour, 1 cup panko breadcrumbs, 2 teaspoons ranch seasoning, and 1/2 teaspoon salt; in bowl 3 beat 2 eggs with 2 tablespoons water.
Pat the 1 1/4 pounds chicken tenders dry with paper towels.
Heat about 2 inches of peanut or vegetable oil in a Dutch oven or deep skillet over medium-high heat until it reaches 360–375°F (use a thermometer if available).
Dredge each tender first in the flour mixture, shaking off excess, then dip into the egg mixture, and finally press into the panko mixture to coat evenly.
Fry 4–5 pieces at a time (do not overcrowd) for about 4 minutes per side, turning once, until golden brown and cooked through.
Transfer cooked tenders to a paper towel–lined plate to drain briefly, then serve with ranch dressing.