Place a large skillet over medium-high heat and drizzle in the avocado oil. Add onions and stir. Cook, stirring, until they start to sizzle and stick, then reduce the heat to medium-low and cook for 5 minutes.
Add the squash cubes and stir. cook, stirring occasionally, until the squash is almost tender, about 8-10 minutes. When the squash is softened, add the cuminseed and stir for a minute, then add the jalapeno and ginger. Stir until fragrant.
Add the garam masala, turmeric and salt and stir for a few seconds. Stir in the tomatoes. Cook until the pan is almost dry and the squash is very tender.Serve hot.