Heat oil in a large pot or Dutch oven over medium-high heat. Add cumin and coriander seeds and cook until fragrant, about 1 minute.
Add onions, garlic, and ginger and cook until onions are translucent, about 5 minutes.
Add mixed vegetables and stir to combine.
Add diced tomatoes, coconut milk, turmeric, paprika, garam masala, and salt. Stir to combine.
Bring to a simmer and reduce heat to low. Cover and let simmer until vegetables are tender, about 20 minutes.
Serve hot over rice or with naan bread. Garnish with cilantro, if desired.
