I use beef chuck steak for this. You need something that is not too lean so it remains soft when cooked.
If you don’t have to follow the low fodmap diet, you can use store-bought Japanese curry roux. You can also use regular garam masala and regular milk and use ½ a chopped onion instead of the spring onions. You can also add 1 clove of chopped garlic and regular olive oil instead of the garlic-infused olive oil.