Soak dry split peas in water overnight*, or for at least 1 hour if possible. Then, rinse thoroughly and drain the peas. Set aside.
In a large pot, heat coconut oil over medium. Once heated, add in diced onions and sauté for 2-3 minutes, or until turning translucent (but not browning).
Next, add in garlic and ginger, and sauté for another 1-2 minutes. Then, add cumin, coriander, turmeric, cayenne, and tomato paste. Cook for another 1-2 minutes, stirring frequently.
Once the spices are fragrant, add coconut milk, vegetable broth or water (start with 4 cups), and split peas to the pot, mixing well. Bring to a low boil, then cover with a lid and reduce heat to simmer.
Cook for approximately 50-60 minutes more, stirring occasionally until the peas are cooked to your preference. If the dal appears dry, mix water in ¼ cup at a time.
When the peas are tender, mix in spinach, garam masala, salt & pepper. Turn the heat off and cover the pot to allow spinach to wilt a little. Taste and adjust spices as needed, adding cayenne for more heat, garam masala for sweet spice, or salt to bring the other flavors out.
Serve this split pea dal with a side of basmati rice, cilantro, roti, or lime wedges. Store leftovers in an airtight container in your fridge for up to 3-4 days.