Step 1: The Physics (Equipment & Reinforcement Zone)
You cannot teach loose-leash walking on a flexi-lead. It teaches the dog that constant tension is normal. Use a fixed 6-foot leash (leather or Biothane) and a Front-Clip Harness: when they pull on a front clip, physics turns their shoulders toward you. Load a treat pouch with high-value treats. Wear it on the side you want the dog to walk on.
Before you walk, define Where walking happens. Hold a treat at the seam of your pants (your thigh). When the dog is standing right next to your leg, say "Yes" and feed at your leg. Take one step. Wait for them to find the leg. "Yes" -> feed at the leg. The dog learns the "Vending Machine" is at your thigh, not out in front.
