Step 1: Heat the coconut oil in a large wok or deep skillet over medium heat. Once shimmering, add the black mustard seeds. Allow them to splutter for about 15-20 seconds. Be careful, they will pop!
Step 2: Add the sliced onion, green chilies, and fresh curry leaves to the pan. Sauté for 5-7 minutes, stirring occasionally, until the onions are softened and translucent and the curry leaves are fragrant. Do not let them burn.
Step 3: Add the cubed marrow to the pan. Stir well to coat the marrow with the onion and spice mixture. Cook for 5 minutes, stirring occasionally, until the marrow starts to slightly soften.
Step 4: Stir in the turmeric powder, ground coriander, ground cumin, and red chili powder (if using). Cook for another 2 minutes, stirring constantly to toast the spices and release their aroma.
Step 5: Pour in the full-fat coconut milk. Bring the mixture to a gentle simmer, then reduce the heat to low. Cover the pan and let it cook for 10-15 minutes, or until the marrow is tender but still holds its shape. Stir occasionally to prevent sticking.
Step 6: Remove the lid, taste, and season with salt as needed. If the sauce is too thin, increase the heat slightly and cook uncovered for a few more minutes to reduce it to your desired consistency. Garnish with fresh chopped cilantro before serving. Enjoy your delicious Marrow & Coconut Stir-Fry with Curry Leaves!