Heat the coconut oil in a large skillet over medium heat until shimmering. Add the diced onion and cook, stirring occasionally, until softened and translucent, about 4 minutes.

Add the minced garlic and grated ginger. Stir constantly for 30 seconds until fragrant. Do not let the garlic brown.

Sprinkle in the curry powder, cumin, turmeric, and cayenne (if using). Stir into the onion mixture for 1 minute to bloom the spices. The pan should look dry and smell deeply aromatic.

Add the zucchini and red bell pepper. Stir to coat with the spice mixture. Cook for 3 minutes, letting the vegetables soften slightly but still hold their shape.

Pour in the cherry tomatoes, coconut milk, and water (or broth). Stir well, scraping up any browned bits from the bottom of the pan. Bring to a gentle simmer.

Reduce the heat to medium-low. Let the curry simmer uncovered for 10 minutes, stirring occasionally. The sauce will thicken slightly and the tomatoes will break down. The zucchini should be tender but not mushy.

Season with salt and black pepper. Taste and adjust. If the sauce is too thick, add a splash more water. If too thin, simmer another 2-3 minutes.

Remove from heat. Stir in half the chopped cilantro. Serve over steamed basmati rice or with warm naan. Garnish with remaining cilantro.