Place water, sugar, mint, and lavender or borage, if desired, in a large stainless-steel or nonreactive pan. Bring to boiling; remove from heat and let steep for 20 minutes. Strain mixture through 100 percent-cotton cheesecloth-lined colander.
Add orange juice, lemon juice, and tea to flavored water; chill. Just before serving, add chilled club soda. If desired, sprinkle punch with flower petals and serve with flower ice cubes or ring.
Flower Ice Cubes: Fill ice-cube trays half full with water and place an edible blossom or petal on water in each cube. Freeze until firm, then fill the tray with water and freeze again.
Flower Ice Ring: Fill ring mold half full with water and place edible blossoms or petals on water in ring. Freeze until firm, then fill the mold with water and freeze again.
Make-Ahead Tip: Prepare punch except do not add club soda. Cover and chill up to 24 hours. Prepare Flower Ice Cubes or Flower Ice Ring and freeze. Add club soda to punch before serving.