Heat gas or charcoal grill. Cut 1 (18x12-inch) sheet of heavy-duty foil; spray with cooking spray. Sprinkle both sides of fish fillets with 2 teaspoons of the seasoning mix. Place fish on center of foil sheet. Bring up 2 sides of foil so edges meet. Seal edges, making tight 1/2-inch fold; fold again, allowing space for heat circulation and expansion. Fold other sides to seal.
Place packet on grill over high heat. Cover grill; cook about 10 minutes, rotating packet 1/2 turn after 5 minutes, until fish flakes easily with fork. Let cool slightly; cut into bite-size chunks.
Meanwhile, in large bowl, mix dressing and remaining 4 teaspoons seasoning mix. Add coleslaw mix and chile; toss to coat. Let stand 10 minutes. Meanwhile, wrap stack of tortillas in sheet of foil; place on coolest part of grill 5 to 10 minutes, turning occasionally, until steaming.
To serve, spoon about 1/4 cup fish chunks and 1/4 cup coleslaw mixture onto each tortilla; top with 2 tablespoons radishes. Fold tortillas around filling. Serve with pepper sauce and tomatillo salsa.