Heat 1 tablespoon of the olive oil in a saute pan set over medium-high heat. Place onion rounds in skillet; season with salt and pepper. Cook until fork-tender, about 3 to 4 minutes per side. Transfer to a plate; set aside. Heat 1 tablespoon olive oil in a medium skillet set over medium-low heat. Add the pumpkin seeds, and cook, stirring occasionally, until golden, about 4 minutes, being careful that the seeds don't jump from the skillet as they pop. Set skillet aside to cool. Place 1/2 cup cooked pumpkin seeds in the bowl of a food processor; add a pinch of salt, and pulse until finely ground. With the machine running, slowly add the remaining 6 tablespoons olive oil. Add the lemon juice, and season with salt and pepper. Set the pumpkin vinaigrette aside. When ready to serve, combine both lettuces and the onion in a large bowl. Pour the reserved vinaigrette over the top, and toss the salad to combine. Sprinkle with remaining 1/2 cup pumpkin seeds.