Toast the curry powder and garam masala in a small skillet over medium-high heat, stirring constantly, until the spices darken slightly and become fragrant, about 1 minute. Transfer the toasted spices to a small bowl.

Pulse the tomatoes and their juice in a food processor until they are coarsely chopped, about 3 to 4 pulses.

Heat the majority of the oil in a Dutch oven over medium-high heat until shimmering. Add the onions and cook, stirring occasionally, until they are well-browned and caramelized, about 10 minutes.

Reduce the heat to medium. Clear the center of the pot and add the remaining oil, garlic, ginger, serrano, and tomato paste. Cook, mashing the mixture into the pot, until fragrant and the paste begins to darken, about 1 minute.

Add the cauliflower and tempeh to the pot and stir constantly until they are thoroughly coated with the aromatics and spices.

Stir in the processed tomatoes, water, and salt, using a wooden spoon to scrape up any browned bits from the bottom of the pot. Increase the heat to medium-high and bring to a simmer.

Cover the pot, reduce the heat to medium, and cook, stirring occasionally, until the cauliflower and tempeh are tender, 10 to 15 minutes.

Stir in the peas and coconut milk and cook until heated through, about 2 minutes. Remove from the heat, adjust salt to taste, and garnish with cilantro.

Serve hot with rice or flatbread.