In a large bowl, combine diced boneless skinless chicken thighs, vegetable oil, minced garlic, salt, pepper, and cornstarch. Mix until the chicken is well-coated and let it sit for 10 minutes.

Heat a large skillet over medium-high heat and add enough vegetable oil to cover the bottom. Wait until it shimmers.

Add the marinated chicken to the skillet in batches, frying for about 4-5 minutes until golden and crispy. Remove and let drain on paper towels.

In the same skillet, sauté sliced bell peppers for 3-4 minutes. Add minced garlic and ginger, cooking for another minute.

Return the chicken to the skillet, then add steamed green beans, sweet chili sauce, sesame oil, and crushed red pepper. Stir well and cook for 2-3 minutes.

Serve the stir fry warm over steamed rice.