Add the olive oil to a large skillet over medium-high heat and cook the soy sausage links, remove and set aside. When cooled a bit, cut into small pieces
Meanwhile, add more oil to the skillet if needed and cook the onion until it begins to brown. Add the garlic during the last few minutes of cooking.
Add the sausage pieces to the onion mixture, stir and add the three or four tablespoons of tomato sauce. Stir until all is incorporated. Remove and place in a medium-sized bowl.
Once cool to the touch, add the breadcrumbs and cheese to the sausage mixture, along with the salt, pepper and red pepper flakes and stir to incorporate.
5.Stuff the mixture into the peppers, packing it gently, all the way to the bottom of each pepper. There should be extra stuffing remaining. Add the two-thirds cup of tomato sauce to the extra stuffing, mix together and keep warm. Use this to top the peppers when ready to serve.
Cover the ends of the peppers with a small piece of aluminum foil so the stuffing doesn't fall out.
Brush the peppers lightly with oil and place on the grill over medium heat.
Cook the peppers, turning once, for about two minutes on each side until they begin to acquire grill marks, then remove
Remove the aluminum foil and place the stuffed peppers on a serving platter. Top with remaining stuffing mixture and serve warm.