Heat the large skillet over medium-high and add the coconut oil until melted and shimmering.
Add the cubed chicken and cook until golden brown on all sides, turning every 2–3 minutes so pieces brown evenly, about 8–10 minutes total depending on cube size.
Meanwhile, in a medium bowl whisk together the juice and zest of 3 lemons, vegetable broth, light soy sauce (or substitute), cornstarch, and honey until smooth.
Pour the lemon mixture over the cooked chicken, reduce heat to low, cover, and simmer until the sauce thickens and chicken is cooked through, about 8–10 minutes.
Uncover, sprinkle with poppy seeds and diced green onions, stir lightly to combine, then serve.