For the shrimp marinade:
1/2 teaspoon kosher salt
1/4 teaspoon ground black pepper
1/8 teaspoon cayenne pepper
2 tablespoons freshly squeezed lemon juice (from about 1 lemon)
1-2 pounds large or extra-large shrimp, peeled and deveined

For the sauce:
1 tablespoon canola oil
1 medium red or yellow onion, finely chopped
1 teaspoon ground pepper
1 tablespoon minced fresh ginger, from about a 1-inch peeled piece of ginger
1 tablespoon kosher salt
2 garlic cloves, peeled and finely minced
2 teaspoons ground coriander
1/2 teaspoon turmeric
1 teaspoon curry powder
1 (14.5-ounce) can diced tomatoes, undrained
1 can coconut milk, light or regular
1 cup chopped fresh cilantro

Hot cooked rice for serving, if desired