Measure and cook the rice in a medium saucepan, following package instructions, until fluffy and tender. Set aside.
Combine the chicken pieces with minced garlic, soy sauce, and a pinch of salt and pepper in a bowl. Toss to coat evenly and marinate for 5 minutes.
1 lb boneless, skinless chicken thighs
Heat vegetable oil in a large skillet or wok over medium-high heat until shimmering. Add the marinated chicken and cook, stirring frequently, until browned and cooked through, about 7-8 minutes. Remove chicken and set aside.
1 lb boneless, skinless chicken thighs
In the same skillet, add mixed vegetables and stir-fry over high heat until tender-crisp, about 3-4 minutes. Push vegetables to the side of the pan.
1 lb boneless, skinless chicken thighs
Return the cooked chicken to the skillet with the vegetables. Stir in the brown sugar and cook, stirring constantly, until the sugar dissolves and the mixture begins to bubble and thicken slightly, about 2-3 minutes. The sauce should turn glossy and sticky, coating the chicken and veggies evenly.
1 lb boneless, skinless chicken thighs
Serve the glazed chicken and vegetables over the cooked rice, ensuring the glossy sauce is spooned generously over the top. Garnish as desired.