Prepare the meat, squash, and beans beforehand. In particular, squash can be a lot of work to peel. If you try and to it after the cooking has started you will fail.
Saute oil, garlic, and onion on medium heat (5 min). Add shrimp till cooked (1–2 min). Set aside.
Put coconut milk and fish sauce in a large pot and bring to a boil while stirring regularly.
Add squash and simmer for 8–12 minutes.
Add saute (which had been set aside), beans, and leaves, and simmer for 3–5 minutes.
Remove from heat, add salt and pepper to taste. Serve with rice.