Frozen Peaches With Strawberries and Mint

Sprinkle sugar evenly across bottom of a large straight-sided skillet or Dutch oven and place peaches, cut sides up, in a single layer on top. Scrape in vanilla seeds and add pod; scatter spearmint over. Pour in water to come halfway up sides of peaches. Bring to a very gentle simmer over low heat, stirring once or twice just to dissolve sugar. Cook peaches, turning once, until tender but not falling apart, 5 –10 minutes. Let cool. Pluck out vanilla pod and spearmint from pot; discard. Stir in lemon juice. Remove skins from peaches (they should slip off easily). Transfer peaches, cut side down, to a 3-qt. shallow baking dish and pour poaching liquid over. Freeze until peaches are icy all the way through but still soft enough to cut with a spoon, 45 –60 minutes (poaching liquid should be semifrozen and break into shards when scraped with a fork, just like granita). Scatter strawberries over peaches just before serving.