Begin by toasting the black peppercorns, coriander seeds, cumin seeds, fennel seeds, and poppy seeds in a dry skillet over medium heat for about 3-4 minutes until fragrant. Transfer these browned spices to a blender, add the unsweetened grated coconut and a splash of water, then blend until you achieve a smooth, rich masala paste.

In a Dutch oven, heat two tablespoons of sesame or canola oil over medium heat. Once the oil is shimmering, add the black mustard seeds and sauté until they start to pop. Then, add the ginger and garlic paste, along with the chopped red onion and fine sea salt. Cook for about 5-7 minutes, stirring occasionally, until the onions are softened and translucent.

Stir in the ground coriander, ground cumin, Kashmiri red chile powder, and ground turmeric along with the fresh bird's-eye chiles into the pot. Cook for another 2-3 minutes until the spices release their fragrant aroma, continuously stirring.

Add the chopped plum tomatoes to the pot, stirring to incorporate everything well. Let this mixture simmer for about 10 minutes, until the tomatoes break down and the oil starts to separate from the sauce.

Pour in the prepared masala paste, followed by the boneless beef chuck, and add enough water to cover the meat. Bring to a gentle simmer, cover, and let it cook for 40-50 minutes on low heat, stirring occasionally.

Stir in half of the unsweetened coconut milk after the beef is tender. If using cubed medium potatoes, add them now, then cover and simmer for an additional 15-20 minutes until the potatoes are cooked through.

Add the remaining coconut milk to the pot, stirring well to combine. Allow the curry to simmer for a few more minutes, then taste and adjust the seasoning as needed.