Step 1Peel the jicama and cut it into 3-inch-long strips that are about one-quarter-inch wide and thick. Repeat with the carrots. Peel and seed the cucumbers, then cut into strips that are about the same size. Peel the onions, quarter lengthwise, then cut into quarter-inch strips.
Step 2Place the sliced vegetables in a large serving bowl. Add the jalapenos (amount depends on desired heat). Toss to combine thoroughly.
Step 3Mix together the lime juice, sugar and salt. Pour over the vegetables and toss. Refrigerate, turning occasionally, for at least two hours.
Step 4Add the cilantro, toss and serve. Serve as finger food before dinner, or add to fajitas, or both.