First, prepare the stew. Heat the oil in a large saucepan over medium heat. Add the onion and sauté until soft, stirring often, for about 15 minutes. Add the garlic and stir for 1 minute. Add the dry spices. Add 1 cup water, lentils (with liquid from the can or reserved 1/4 cup cooking water), and lemon juice. Bring the mixture to a boil. Add the squash and carrots. Cover and simmer over medium-low heat. Stir occasionally and cook for about 20 minutes, or until the vegetables are tender. Keep warm until the quinoa is finished, or cover the stew and refrigerate until ready to serve.
Next, prepare the quinoa. Place the oil in a large saucepan over medium heat. Add the onion and cook, covered, until translucent, about 3 to 5 minutes, stirring often so the onion does not burn. Add the garlic, salt, and turmeric, and sauté for one minute. Add the quinoa and stir for one minute. Add 2 cups of water. Bring to a boil and then reduce the heat to medium-low. Cover and simmer until all the liquid is absorbed and the quinoa is tender, for about 15 minutes.
To serve, stir half the cilantro and half of the basil into the warm stew. Spoon the quinoa onto a platter or divide among bowls and form a well in the center. Spoon the stew into the well and garnish with the remaining cilantro and basil, if desired.