Preheat oven to 400°.
Slice squashes in half along the equator.  You might also want to slice the top and bottom off so that they squashes will sit flat.
Scoop out the seeds and membranes from the inside of squash.
Drizzle a tiny bit of oil on the squashes and place them face down on a parchment lined baking sheet.
Roast squash halves for 20-30 minutes, until they are able to be easily pierced with a fork.
Heat oil in a medium pot over medium heat.
Add onions and begin to brown.
Add garlic and brown.
Add salt, sugar, and curry powder.  Stir well.
Add tomatoes, lentils, and water.
Bring to a boil, then reduce to a simmer.
Simmer until lentils are al dente, about 20 minutes.
Remove squash from the oven.
Fill each squash half with a scoop of the lentil mixture.  Enjoy!