Heat the oil in a Dutch oven or large deep skillet and add the sliced red peppers once the oil is warmed. Cook until almost done, about 5 minutes. Leave a little crunch in them as they'll finish cooking in the coconut milk.
Add the garlic, 1/4 cup of the cilantro, red pepper flakes and the white parts of the green onions. Cook another minute, stirring.
Add the coconut milk and tomatoes. Bring to a simmer and cook about 5 more minutes, stirring.
Add the shrimp and partially cover the pan. Cook 5 more minutes or so, until the shrimp is cooked through. Add the cooked chicken and heat through, stirring.
Stir in the lime juice and then taste, adding more salt if needed.
Serve on a bed of steamed rice, with the rest of the cilantro and the green parts of the onion sprinkled on top.