Rinse the lentils in a colander. Combine them in a saucepan with the apple juice, ginger, and water. Bring to a boil, then lower the heat and simmer, uncovered, for 30 to 40 minutes, until the lentils are tender. Add a little water near the end of cooking if necessary to prevent sticking.
While the lentils cook, saute the onions, garlic, and carrots in the oil for about 5 minutes, until the onions begin to soften. Add the bell peppers, zucchini or squash, and tomatoes, cover, and cook on low heat for about 10 minutes, until just tender. Stir in the soy sauce and vinegar.
When the lentils are ready, combine them with the vegetables. Serve on rice and top with chopped scallions.