Fill a large saucepan with water and bring to a boil. 

Peel the carrots, quarter lengthwise, then cut crosswise into ¼-inch pieces. Trim the ends off the scallions, then thinly slice. Finely chop 2 teaspoons garlic. 

In a small bowl, combine tamari soy sauce, ¼ cup vinegar, 2 tablespoons water, and 4 teaspoons sugar. Stir until the sugar is dissolved. 

Add rice to boiling water; cook (like pasta), stirring occasionally, until almost tender, 6–7 minutes. 

Add half the carrots and cook, stirring occasionally, until tender, 3–4 minutes. Use a fine-mesh sieve to drain rice and carrots; rinse under cold water and drain again. Set aside.

Pat chicken dry; season with salt and pepper. Heat 1 tablespoon oil in a large nonstick skillet over medium-high. Add chicken and cook until it’s golden brown on the bottom, about 4 minutes. 

Flip the chicken, then add the soy sauce mixture to the skillet. Cook until chicken is cooked through and sauce is reduced to about ⅓ cup, about 2 minutes.

Remove skillet from heat. Turn chicken to coat in the soy glaze, then transfer to a plate; cover to keep warm.

Transfer glaze to a bowl. 

Rinse out the skillet and wipe dry. Heat 2 tablespoons oil in the same skillet over medium-high heat. Add the chopped garlic and half of the scallions. Cook, stirring, until fragrant, about 30 seconds. 

Add peas, rice, and carrots to the skillet. Cook over medium-high heat, stirring, until rice is heated through, about 2 minutes.

Return glaze to skillet, stirring to coat rice. Serve soy glazed chicken and any resting juices over vegetable fried rice. Sprinkle remaining scallions over top.