Chop cauliflower into bite-sized florets and potatoes into even cubes. Slice onion thinly, and finely mince garlic and ginger until fragrant (about 5 minutes total prep).

Heat cumin seeds in a dry skillet over medium heat, stirring until seeds pop and turn golden brown (about 1 minute).

Stir in turmeric, chili powder, and garam masala into toasted cumin seeds, cooking for 30 seconds, then transfer the blend into your slow cooker.

Layer potatoes, cauliflower, sliced onion, minced garlic, ginger, and diced tomatoes in the slow cooker. Pour in 1/4 cup vegetable broth or water to prevent sticking.

Cover and set to low for 6 hours (or high for 3–4 hours) until veggies are tender.

Season with salt to taste, gently stir to blend spices, then sprinkle fresh cilantro leaves before serving warm.