Preheat the oven to 375°F. Line a 9 x 13-inch baking pan with foil (for easy cleanup).
Lay the peppers on their sides. Slice off the top one-third of the peppers, just above the stem, to make little "boats" for stuffing. Finely dice enough of the sliced-off pieces to get 1 cup. (Save any remaining pieces of pepper for a snack.)
Cut out the seeds and as much of the ribs as you can to make room for the stuffing. Place the pepper boats cut side down in the pan and bake for 10 minutes to soften. Remove from the oven and flip the peppers cut side up. Leave the oven on.
Meanwhile, in a large nonstick skillet, heat 2 teaspoons of the oil over medium-high heat. Add the diced pepper and salt and cook for 2 minutes to soften. Add the remaining 1 teaspoon oil and the chicken to the pan and cook, breaking the chicken into crumbles with a spoon, for 1 minute, or until still a little pink. Off the heat, stir in the almonds and let cool slightly.
In a small bowl, beat the egg with the tamari. Beat in the tomato paste. Stir into the chicken mixture.
Divide the stuffing evenly among the peppers. Cover the pan with foil and return to the oven. Bake for 20 minutes, or until the peppers are tender and the stuffing is cooked through.
Uncover and sprinkle the peppers with the feta. Re-cover and let sit at room temperature for 5 minutes before serving.