2 tablespoons peanut oil or olive oil, divided
1/2 teaspoon kosher salt, divided
1/2 pound boneless pork loin chop, cut into 1/2-inch pieces
1/2 cup chopped carrot
1/2 cup chopped celery
1/2 cup chopped green onion bottoms (white part)
2 tablespoons minced garlic
2 tablespoons minced peeled fresh ginger
3 cups cooked, chilled long-grain brown rice
1 large egg
3 tablespoons mirin
3 tablespoons lower-sodium soy sauce
1 teaspoon dark sesame oil
1/4 teaspoon freshly ground black pepper
2 cups fresh bean sprouts
1/4 cup canned diced water chestnuts, rinsed and drained
1 cup chopped green onion tops