To prepare the vinaigrette, combine the ingredients in a jar with a tight-fitting lid and shake vigorously until emulsified.
To prepare the salad, cut the squash in half lengthwise, brush the cut sides with olive oil and season with salt and pepper.
Grill the squash, cut-side down, over medium-hot coals, or in a cast-iron grill pan over high heat.
When grill marks appear, turn over the squash and grill the skin side briefly—about 1 to 3 minutes.
Cool the squash slightly, then cut into ½-inch slices on the diagonal.
Place the lentils into a large bowl, add the squash, herbs, pumpkin seeds and vinaigrette and toss thoroughly.
Season to taste with salt and freshly ground pepper and toss again. This salad keeps and travels well.