Heat the oil in a large wok over medium heat until it shimmers, then add cumin seeds and bay leaf. Sizzle for about 30 seconds until fragrant.
Add the sliced onions and cook, stirring often, until they become translucent and slightly golden, about 5 minutes. The onions should smell sweet and aromatic.
Stir in the crushed ginger and garlic paste, cooking for about 1 minute until fragrant and slightly bubbling.
Add the turmeric, cumin powder, and garam masala, stirring quickly to toast the spices for about 30 seconds until fragrant, then pour in the chopped tomatoes. Cook this mixture for 10 minutes, stirring occasionally, until the oil separates and the sauce thickens.
Add the sliced bell peppers and carrots to the pan, stirring well to coat them with the spice sauce. Cook for about 8-10 minutes, stirring frequently, until the vegetables are tender but still vibrant and slightly crisp.
Taste the dish and add salt as needed. If the sauce is too thick, add a splash of water and simmer a couple more minutes to loosen it slightly.
Remove from heat and stir in chopped cilantro, allowing its fresh aroma to infuse the dish. Serve hot over steamed rice or with flatbread, garnished with extra cilantro if desired.