Toss the grated zucchini with the salt in a medium bowl and let it stand for 10 minutes until the liquid has been extracted; do not drain this liquid, as it hydrates the dough.

Prepare a steamer by placing a steaming ring or ramekin in a large pot with a few inches of water, ensuring the water level stays below the ring. Bring to a boil, then reduce the heat to a gentle simmer and cover.

Whisk together the flour, semolina, sugar, turmeric, and baking soda in a large bowl. Add the salted zucchini and its liquid along with the ginger, garlic, chili, and lemon juice, mixing until a very loose dough forms that still holds its shape.

Form the dough into logs about 1 inch in diameter using lightly oiled hands. Arrange the logs 1 inch apart on an oiled perforated steaming dish and steam until a toothpick inserted into the center comes out clean, about 15 to 20 minutes.

Transfer the logs to a plate and cover with a damp kitchen towel. Allow them to cool and firm up for at least 30 minutes before slicing them into half-inch disks.

Heat the oil in a large nonstick pan over medium-high heat until the mustard seeds begin to pop. Reduce the heat to low, stir in the sesame seeds and curry leaves for 30 seconds, then add the dumpling disks.

Increase the heat to medium-high and cook the disks for 3 to 5 minutes, stirring frequently, until they are deeply browned. Stir in a few tablespoons of water at the very end to ensure they remain moist and tender.

Serve immediately while hot, topped with fresh cilantro and your choice of chutney, yogurt, or ketchup.