1. Layer cabbage and lettuce leaves around the inside of a 10-inch footed bowl and let the leaves hang over the edge.
2. Place an 8-inch square of floral foam (about $2, available at crafts stores) in the bowl and slowly pour a cup of water over the foam; let it soak for 20 minutes.
3. Arrange the vegetables: Stick artichokes and asparagus directly into the side of the foam and arrange small heads of purple cauliflower around them; fill in the gaps with sage leaves and leftover cabbage.