bring saucepan of water to boil. add salt and lentils, return to boil, then let simmer covered for about 45 minutes. preheat oven to 400, oil a 9x13 baking sheet, and spread out butternut squash (which has been tossed with olive oil, salt, and pepper). roast about 30 minutes, stirring them halfway through. in large skillet, heat olive oil over med heat. add onion and cook 5 minutes until soft. add garlic and cook 30 seconds, then pour in tomatoes, sage, and cooked lentils (drained if necessary). stir in stock and season to taste with salt and pepper. (partially blend with immersion blender for creamier sauce) stir in roasted squash and keep warm over low heat. bring large pot of water to boil and cook linguine until al dente. drain pasta. serve sauce over pasta.
