Preheat the oven to 400 degrees.
Add the lentils to a medium saucepan and cover with at least two inches of water. Cover, bring to a boil, then reduce to low and simmer for 15-25 minutes, or until the lentils are just tender but not mushy. Cooking times vary depending on the type of lentils used, so start testing at 15 minutes. Drain and set aside.
Meanwhile, slice the delicata squash in half lengthwise and remove the seeds. Slice each half into 1-inch slices (you should end up with half-moon shaped pieces).
Place the sliced squash on a baking sheet, drizzle with 1 tablespoon olive oil, and sprinkle with ¼ teaspoon salt. Place in the oven and roast for 20-25 minutes, flipping halfway through, or until the squash is golden brown on each side and cooked through.
At the same time, place the pumpkin seeds on a baking pan or pie dish and toast in the oven for 10 minutes, or until lightly toasted and brown. Keep a close eye on the seeds, as they can burn easily.
Meanwhile, make the dressing by whisking the vinegar, garlic, maple syrup, mustard, and salt in a medium bowl. Drizzle in the olive oil and whisk until the dressing is smooth and creamy.
Combine the warm, drained lentils with the dressing in a large bowl, tossing to combine. Let sit for 5 minutes for the dressing to absorb.
When ready to serve, toss the dressed lentils with the roasted squash, pumpkin seeds, and greens. Serve immediately.