In a fine-mesh sieve or colander, mix the onion with ½ teaspoon of the kosher salt. Set aside for 5 minutes, then rinse under cold water. Transfer the onion to a paper towel and set aside.
In a large skillet set over medium heat, melt the butter. Add the pistachios and cook, shaking the pan often, until the pistachios are golden-brown, 3 to 4 minutes. Stir in ½ teaspoon of the kosher salt and turn the pistachios out onto a large plate to cool.
In a salad bowl, whisk together the Bonne Maman Strawberry Preserves, oil, remaining ½ teaspoon of salt, black pepper and the juice of 1 lime half. Add the spinach, onion and pistachios and toss to coat. Squeeze the remaining lime half over the salad, gently toss and serve.