In large pot of boiling water, cook cauliflower and carrots for 2 minutes; drain and transfer to ice water bath. In same pot, bring 2 cups water, the vinegar, sugar and salt to boil. Add cooked cauliflower and carrots, fennel, onions, jalapenos, mustard seeds and celery seeds and return to boil; remove from heat. With slotted spoon, transfer vegetables to 2 hot, sterilized 1-qt. jars. Ladle in hot pickling liquid, leaving 1/2 inch headspace; seal jars. In water-bath canner, process jars for 15 minutes.