In a large skillet over medium high heat, add the olive oil. Once hot, add the diced onions and cook for 3-4 minutes until softened, stirring continuously.
Add the crushed garlic, and cook for a further minute or so, then add the minced beef.
Cook for a minute, breaking apart any clumps of meat with a wooden spoon, cooking, a good 6-8 minutes until beef is all cooked through and brown with no pink bits remaining. Keep stirring and breaking apart clumps of meat.
If desired, drain any extra fat. Add all the spices (seven spice or all spice, cinnamon, salt and black pepper) and stir to combine. Taste the mince and adjust for seasoning. Stir in the toasted nuts.
Using a small spoon, or even better your hands, stuff the hollowed out zucchini all the way to the top with cooked beef. Make sure it's stuffed tight and compact, press in with your finger at the very top to indent the meat inside. This will prevent meat from coming out as it cooks in the yogurt sauce. Set the stuffed zucchini aside.