Steam squash in a steamer basket set in a pot of simmering water until tender, 68 minutes. Let cool slightly. Heat 1 Tbsp. oil in a large skillet and cook squash, turning occasionally, until browned, about 5 minutes. Transfer to a plate. Heat remaining 1 Tbsp. oil in same skillet, add sausage, and cook, breaking into large pieces and stirring occasionally, until browned and cooked through, about 5 minutes. Add scallions, garlic, chile, and ginger and cook, stirring often, just until softened, about 2 minutes. Add squash, lime juice, fish sauce, and sugar; toss to combine. Serve stir-fry topped with peanuts and cilantro.