Green Mango and Cashew Salad

2 cloves garlic, smashed
8 thin slices ginger
2 to 4 Thai bird chilies
3 tbsp. fresh lime juice
1 tbsp. Thai palm sugar or light brown sugar
1 tbsp. fish salt
Pinch sea or kosher salt
1⁄4 cup thinly sliced shallots
2 to 3 unripe mangos, peeled, seeds removed, cut into matchstick strips to yield 6 cups
2 tsp. finely sliced kaffir lime leaves or 1 tsp. minced lime zest
1⁄4 cup roughly chopped coriander leaves
1⁄4 cup crushed or chopped toasted cashews