Melt the butter in a large microwave-safe bowl. Stir in the sugar and crushed pretzels. Press pretzel mixture across bottom and up sides of a greased glass pie plate. Keep chilled until ready to use.

Make filling: Purée strawberries, zest, lime juice, condensed milk, tequila, and liqueur in a blender or food processor until smooth, then transfer to a large bowl.

Beat cream to stiff peaks. Fold one third of cream into strawberry mixture gently but thoroughly to lighten, then fold in remainder in 2 batches.

Pour filling into crust, mounding it slightly, and freeze, uncovered, until firm, about 4 hours. Remove from freezer and let soften in refrigerator, about 40 minutes, before serving (pie should be semisoft).