In a large pan, melt the butter over medium heat. Add the mushrooms and sauté for about 5 minutes, until they start to release their juices.
Add the diced carrot and sauté for another 2-3 minutes, until they begin to soften.
Add the green peas, cilantro, and chopped tomato. Stir to combine.
In a small bowl, whisk together the coconut milk, soy sauce, tomato sauce, and curry paste.
Bring the mixture to a simmer, and let it cook for about 10-15 minutes, until the vegetables are tender and the sauce has thickened.
Taste and adjust the seasoning, adding salt as needed.
Serve the curry hot, garnished with extra cilantro leaves if desired. It can be served over steamed Rice or with Naan bread.