Inspired by Saiphin Moore. If you are using commercial curry paste, this dish will be pretty spicy; if you would like to make it homemade (always my preference) here is a link to a homemade red Thai curry paste recipe. Some fresh basil or cilantro at the end will make this even better, but if you do not have either, the dish will still be great without it.
Heat the coconut oil in a large, heavy pot or deep pan over medium high heat. When it is melted and hot, add the curry paste. Stir the curry paste into the coconut oil and fry for a few minutes, until the paste is quite fragrant and beginning to separate from the oil.
Add the onions and prepped parval and stir into the curry paste. Stir and let the veggies fry for about 5 minutes.
Add the mushrooms with a tiny pinch of salt. Stir and let the veggies fry together. When they have released most of their water and are starting to caramelize, add the ground beef.
Mix the ground beef into the vegetables. Cook, stirring, until the meat is mostly browned.
Add the canned tomatoes with the 2 tablespoons palm sugar. Stir and let the tomatoes simmer for 5 minutes, stirring occasionally.
Add the coconut milk and 1 tablespoon fish sauce. Stir to incorporate the coconut milk. Reduce the heat to a simmer and let the curry simmer for 5 minutes to meld the flavors. Add the pineapple and let the dish simmer another 5 minutes.
Taste for more palm sugar (sweet) and fish sauce (salty/umami). The tomatoes should provide enough acid.
Garnish with fresh basil or cilantro if using (highly recommended!) and serve hot over jasmine rice.