Jicama and blood orange salad

1 jicama, about 3/4 lb
3 blood oranges
1 papaya or mango or 1/4 pineapple
1 small red (Spanish) onion, thinly sliced
1 teaspoon sea salt
1/4 dried habanero chili pepper, seeded and finely chopped or ground to a powder, or cayenne pepper to taste (optional)
3 tablespoons olive oil
Juice of 1 lime
1 bunch fresh cilantro (fresh coriander), about 3 oz, stemmed
1 bunch fresh mint, about 3 oz, stemmed

1. Using a paring knife, peel the jicama, including the fibrous layer just beneath the skin. Thinly slice the flesh and then cut into thin strips 2 inches long and 1/4 inch thick. Place in a large bowl.
2. Working with 1 orange at a time and using a sharp knife, cut a slice off the top and bottom of the oranges to reveal the fruit. Place each orange upright on a cutting board and cut away the peel and any white membrane. Then, holding the orange over the bowl with the jicama, cut along either side of each segment to free it, letting the segments and any juices fall into the bowl. If using a papaya, halve lengthwise, scoop out and discard the seeds and peel the halves. If using a mango, peel it and cut the flesh from the pit. If using pineapple, cut away the peel and the tough core area. Cut the papaya, mango or pineapple into 1/2-inch dice; you should have about 1 1/2 cups. Add to the bowl.
3. Add the onion, salt, habanero chili or cayenne pepper, olive oil, lime juice, cilantro and mint to the bowl. Toss gently to mix. Cover and refrigerate for 2 hours before serving.