Prepare ingredients: dice the onion, thinly slice the red and yellow bell peppers, chop the celery, peel and slice the carrots, and cut the chicken breasts into bite-size pieces; season the chicken lightly with salt and pepper.
Heat a large skillet or wok over medium heat and add 1 tablespoon olive oil.
Add the onion, bell peppers, celery, and carrots (but not the edamame) to the skillet and sauté, stirring occasionally, for about 3 minutes until they begin to soften.
Add the chicken pieces to the skillet and stir to combine with the vegetables.
Pour in the light soy sauce and lemon juice, then sprinkle in the red pepper flakes; stir and continue cooking for about 12–15 minutes, stirring occasionally, until the chicken is cooked through and vegetables are tender.
Stir in the edamame in the last 2–3 minutes of cooking to heat through; adjust seasoning with additional salt and pepper if needed.
Remove from heat and serve immediately.
