Thai Mango-Prawn Salad

Ingredients

• 2 tablespoons peanut oil
• 1 pound large shrimp, peeled and deveined
• 1 tablespoon chopped garlic
• 1 1/2 teaspoons chopped pickled ginger
• 1/2 cup mirin (Japanese sweet wine)
• 1 tablespoon fish sauce
• 1 tablespoon rice vinegar
• 1/2 red pepper flakes, or more to taste
• 1 red onion, thinly sliced
• 1/2 cup matchstick-cut carrots
• 1/4 cup chopped cashews
• 1/4 cup chopped green onions, or more to taste
• 1 ripe mango, cubed
• 1/2 lime, juiced
• 1/2 teaspoon soy sauce, or more to taste
• 1 pinch white sugar
• 1 romaine hearts, chopped into bite-sized pieces, or more to taste