In a skillet, toast the coconut over medium heat until golden brown, then transfer to a bowl. Add 1 tablespoon of coconut oil to the same skillet. Sauté the chopped onion, minced garlic, grated ginger, and chopped serrano pepper for 3-5 minutes until softened and fragrant.

Add the chopped zucchini, chopped summer squash, spicy curry powder, garam masala, salt, and pepper to the skillet. Cook for 5 minutes, stirring occasionally, until the vegetables are tender-crisp and the spices are aromatic.

Pour in the diced tomatoes (with their juice) and 1 cup of water. Bring the mixture to a boil, then reduce the heat and simmer for 10-15 minutes, or until the sauce has thickened to your desired consistency.

While the masala simmers, prepare the rava dosai batter. In a bowl, combine the semolina flour, rice flour, all-purpose flour, chopped green onion, cumin seeds, salt, and pepper. Gradually whisk in 2 cups of water until you achieve a thin, smooth batter; add more water if necessary.

Heat a nonstick skillet or griddle over medium-high heat and generously grease it with oil. Stir the dosa batter well. Pour about 1/2 cup of batter into the hot skillet, immediately spreading it in a rapid circular motion to form a thin, even crepe. Drizzle about 1 teaspoon of oil or butter around the edges and over the top of the crepe while it cooks.

Cook the dosa for approximately 2 minutes, or until the edges begin to lift and the underside is golden brown and spotted. Carefully flip the dosa and cook for another minute. Transfer the cooked dosa to a plate and repeat the process with the remaining batter, keeping the dosas warm.

Stir the coconut milk into the thickened vegetable masala until well combined. Remove the masala from the heat. Stir in the fresh chopped cilantro and the toasted coconut.

To serve, spoon a generous portion of the masala onto one half of a warm dosa. Fold the other half of the dosa over the filling to create a half-moon shape. Garnish with additional fresh cilantro if desired.