Heat 1 tablespoon of the oil over medium high heat in a large sauté pan. When oil is shimmering, reduce heat to medium and add mustard and cumin seed. Temper the spices, cooking and stirring until they are fragrant and starting to pop in the oil.
Add garlic, ginger, chile and hing to pan, stirring to combine. Cook until fragrant, about 45 seconds.
Add onion to pan, drizzling in a little more oil, if needed. Stir to combine and cook, stirring frequently, until onion starts to soften, about 3 minutes. Don’t brown the onion—reduce heat, if needed.
Add tomato to pan and stir to combine. Cook, stirring frequently, for about 4 minutes. Add chile powder, garam masala, coriander and cinnamon to the pan and stir to combine. Cook for about 3 minutes, stirring occasionally.
Add water and scrape up any browned bits. Add butter beans. Raise heat and bring to a boil, then reduce the heat and simmer for about 10 minutes, partially covered, until all the flavors have combined and developed. Taste and adjust seasoning with salt, if needed.
Serve over cook rice in shallow bowls. You can also serve it with naan or roti.