Bring a large pot of lightly salted water to a boil. When boiling, place the oil in a large skillet set over medium heat. Add the bell pepper and cook 2 minutes. While the peppers cook, boil the ravioli until tender, about 3 to 4 minutes.
When the peppers have cooked 2 minutes, add the yams to the skillet and cook 1 minute. When the ravioli is cooked, reserve cup of the cooking liquid before draining it well. Add the ravioli, reserved cooking liquid, spinach, pesto, salt and pepper to the skillet and toss to coat. Cook a minute or two, until the spinach is just wilted, and then divide among serving bowls. Let diners sprinkle the ravioli with Parmesan cheese to taste. If desired, they could also drizzle the ravioli with a little olive oil.
Note: To parboil the yam, set in a pot and cover with 2" of cold water. Bring to a simmer, and simmer until just tender, about 4 to 5 minutes. Drain, cool in cold water, drain again, and it’s ready to use.