In a bowl, combine sauce ingredients. Set aside.
Season tuna with salt and pepper. Place sesame seeds in a shallow dish, then coat tuna with sesame seeds.
In a skillet, heat oil over medium heat. Sear the tuna for 1 to 2 minutes on each side. Transfer to a plate, then cut tuna into thin slices.
In a pot of boiling salted water, cook edamame for 3 to 5 minutes. Drain. Rinse with cold water and drain again.
Meanwhile, cook rice according to package directions. Let cool.
In four bowls, divide rice, tuna slices, edamame, mango and sweet peas. Garnish with green onions and drizzle sauce over top.