For ultimate freshness, prepare this treat right before serving. Present it with toothpicks for spearing the fruit and a bowl of your favorite dip, if desired.
Hull and halve 29 large strawberries and set them aside.
Arrange 30 large blackberries, as shown, in the upper left corner of a serving tray or cutting board (it should be at least 8 by 13 inches).
Cut 58 banana slices, 3/4-inch-thick, into a bowl. Sprinkle on lemon juice and toss the slices gently with a rubber spatula to keep them from browning.
Assemble the banana slices in rows as shown and top each slice with a strawberry half.