1. Preheat the oven to 350°F.
2. Drizzle a rimmed baking sheet and the flesh of the squash with a little olive oil. Set the squash half cut side down on the baking sheet. Sprinkle 2 tablespoons of water over the squash and bake, uncovered, until a fork inserted into the thickest part of the flesh meets no resistance, 30 to 45 minutes. Let cool to room temperature.
3. In a large nonstick skillet over medium heat, melt the butter. Add the onion and cook, stirring occasionally, until lightly caramelized, about 5 minutes. Set aside.
4. Using a fork, scrape the squash from the skin into a medium bowl; the flesh will separate into spaghetti-like strands (you should have about 2 1/2 cups). Return the skillet with the onion to medium heat and add the squash. Cook, tossing gently, just until heated through, 1 to 2 minutes. Season to taste with Curry Salt; go easy because the cheese will add salt, too. Toss in the cheese and chives and transfer to a serving bowl. Sprinkle with the tomatoes and cilantro and serve right away.
To make Curry Salt:
Mix the salt and curry powder until well combined. Store in an airtight container in a cool, dark place (the flavor of the salt gets better with age). This recipe will not go bad over time.