1. Place fennel, carrots and cauliflower in a large bowl.
2. In a medium pot, combine vinegar, sugar, pickling spice, salt, garlic, rosemary, jalapenos and water. Bring mixture to a boil, reduce to a simmer and cook until sugar is dissolved, about 4 minutes. Let cool 10 minutes, then pour over vegetables; let cool, cover with plastic wrap and chill 4 hours or overnight. (If necessary, place a dinner plate over plastic to keep vegetables submerged.) Store up to a week in liquid; strain before serving.