Season the chicken with salt. Heat 1 tablespoon of the oil in a large skillet over medium-high heat. Add the chicken and cook, stirring occasionally, until it is just cooked through, about 5 minutes. Transfer the chicken to a large bowl.
Add the remaining tablespoon of oil to the pan, then add the shallots, green beans and bell pepper and cook, stirring, until the vegetables are crisp-tender, about 3 minutes. if the pan seems dry while cooking the vegetables, add a splash of the chicken broth. Transfer the vegetables to the bowl with the chicken.
Add the chicken broth, coconut milk, curry paste and the fish sauce to the skillet and bring to a gentle boil, whisking until the curry paste is dissolved. Simmer over medium heat until the sauce is reduced to about 1¼ cups, about 6 minutes. If using pre-cooked packaged rice, follow the directions on the package for heating it up.
Once the sauce is reduced, return the chicken and vegetables to the skillet and cook until warmed through, about 2 minutes. Stir in the spinach and lime juice and cook until the spinach is just wilted, 30 seconds. Serve in bowls over the rice, garnished with the cilantro.
Notes
For the cooked rice, you can certainly make your own cooked brown rice. But you can also buy frozen cooked rice or on-the-shelf cooked rice.
This dish will keep in an airtight container in the refrigerator for up to 4 days.