Chawan Mushi with Shrimp and Spring Peas

INGREDIENTS

• 2 instant dashi powder (Japanese soup stock granules)
• 1 plus 2 teaspoons mirin (sweet Japanese rice wine)
• 2 reduced-sodium soy sauce
• 1/8 toasted sesame oil
• 1/2 shelled fresh peas (from about 1/2 pound pods) or frozen peas, thawed
• 12 baby shrimp or 4 large shrimp, peeled, deveined, coarsely chopped if large
• 4 large shiitake mushroom caps, finely chopped
• 3 large eggs
• 2 scallions, whites and pale greens only, thinly sliced