Working with one breast at a time, place between 2 sheets of waxed paper and pound to 1⁄2–3⁄4” thickness. Repeat with remaining chicken, then place in a sealable freezer bag.
In a bowl, whisk yogurt with Mango Curry Dip Mix, garlic, and Sea Salt. Pour over chicken, seal bag, and pat to coat evenly. Refrigerate at least 2 hours or overnight.
Preheat barbecue to medium-high.
Remove chicken from bag. Using a Corner Spatula, scrape off excess marinade. Discard marinade.
Grill chicken until cooked through, approximately 3–4 minutes per side.