Heat oil in a frying pan over a medium heat. Add onion and cook 10 minutes, until softened, stirring occasionally. Increase heat and add mince, carrot, garlic and cumin. Cook, stirring constantly, to break up mince, until browned. Add ginger, chilies, tomatoes, tomato paste, oregano, thyme and salt.
Reduce heat and simmer 30 minutes, until very thick, stirring occasionally.
Spray a jaffle iron with olive oil spray, then preheat. Spread 1 heaped tablespoon of spicy beef over one slice of bread, make a well in the centre of the beef mixture, then carefully place an egg yolk in the well. Top with a few baby spinach leaves. Gently cover with another bread slice. Repeat with remaining bread.
Carefully place the two sandwiches in the jaffle iron and spray with olive oil spray. Close the lid and cook for 5 minutes or until bread is golden and crunchy.
Refrigerate leftover spicy beef mixture.