In a large bowl, toss the apples with the crystallized ginger, granulated sugar, lime zest, lime juice and a pinch of salt. Spread the apples in a shallow 3-quart baking dish. Sprinkle the topping over the apples and press gently. Bake the crisp for 50 minutes, until bubbling and the top is golden. Let cool for at least 30 minutes before serving with ice cream.