Heat oil in a large nonstick skillet over medium-high heat. Add duck to pan; cook 2 minutes on each side. Reduce heat to medium; cover and cook an additional 3 minutes on each side or until done. Cut duck diagonally across grain into thin slices.
Combine hoisin, orange rind, orange juice, and Sriracha. Heat tortillas according to package directions. Spread about 2 tablespoons hoisin mixture down center of each tortilla. Top each tortilla with 1/4 of duck, 2 cucumber strips, 1/4 of onions, and 1/2 teaspoon sesame seeds; roll up.