Season the beef cubes with salt and black pepper, then heat the vegetable oil in a Dutch oven over medium-high heat and brown the beef in batches until well browned on the outside, about 5 minutes per batch. Keep the browned pieces in the pot while you continue with the remaining beef.

Reduce heat to medium and cook the diced onion for 4 minutes until softened. Add the minced garlic, grated ginger, minced scotch bonnet or habanero (if using), and tomato paste, then cook for 2 minutes, stirring constantly to coat the onions.

Add the crushed tomatoes, beef broth, ground cumin, and ground coriander, then return the browned beef to the pot. Cover and simmer until the flavors deepen, about 1 hour 15 minutes, stirring once or twice so nothing sticks.

Whisk the natural peanut butter into the hot stew until smooth, then add the cubed sweet potato. Keep it at a steady simmer and cook for 30 to 35 minutes, stirring occasionally, until the sweet potato is tender.

Stir in the baby spinach and cook just until wilted, about 2 to 3 minutes. Taste and adjust seasoning if needed, then turn off the heat.

Serve the stew over white rice and top with chopped roasted peanuts and fresh cilantro. Let each bowl sit 1 minute so the peanut sauce clings to the rice before eating.