Fill a large pot halfway with water and bring to a boil; season generously with salt. Prepare an ice bath in a large bowl. Blanch the sugar snap peas in the boiling water for 2 minutes, or until they turn bright green and soften slightly. Strain, then immediately plunge into the ice bath to cool completely. Drain well. Spread out the snap peas on a baking sheet and dry with paper towels.
Heat 1 tablespoon of the olive oil in a large cast-iron skillet over medium-high heat. When the oil is hot, add the prosciutto slices; cook for 1 to 2 minutes per side, until crispy. Transfer to a paper-towel-lined baking sheet to cool and drain of excess oil.
Add the dried sugar snap peas to a large bowl, and crumble the prosciutto over the peas. Drizzle with the remaining 2 tablespoons olive oil. Add the goat cheese, shallots, orange supremes, orange juice, radishes, mint and tarragon; gently toss together. Season with salt and pepper, and serve immediately.
The salad can be held in the refrigerator for a couple hours before serving. After 3 or 4 hours, however, the bright green color of the snap peas will dull slightly, though taste and texture are unaffected.