Curried Spaghetti Squash Fritters

Name: Curried Spaghetti Squash Fritters
Ingredients: ½ English hothouse cucumber, grated; ½ cup plain Greek yogurt; ½ teaspoon finely grated lime zest; 1 tablespoon fresh lime juice; 1 teaspoon brown mustard seeds; Kosher salt; 1 medium spaghetti squash (about 3 pounds); ½ onion, grated; 1 large egg, beaten to blend; ¼ cup chickpea flour; 1 teaspoon curry powder; ½ teaspoon kosher salt; ¼ teaspoon cayenne pepper; Vegetable oil (for frying; about 3 cups); Flaky sea salt (such as Maldon)