If using fresh peaches, freeze sliced peaches on a baking sheet for at least 2 hours. Store-bought frozen peaches can go straight into the blender.
Add frozen peaches and ice to the blender, then pour in water, lemon juice, honey, and vanilla extract.
Blend on high for 45 to 60 seconds until completely smooth and thick. Scrape down sides if needed and blend again briefly.
If too thick, add cold water one tablespoon at a time. If too thin, add more ice and blend again.
Taste and adjust sweetness with more honey or add more lemon juice for extra tang.
Pour into chilled glasses and garnish with a fresh peach slice, mint sprig, and lemon wedge. Serve immediately.