Heat oil in a large pan over medium heat.
Add chopped onion and sauté until softened and lightly golden, about 5-6 minutes.
Add minced ginger, garlic, and green chillies. Cook for 1-2 minutes until fragrant.
Add turmeric powder, ground cumin, and coriander powder. Cook for 30 seconds, stirring constantly.
Add baby spinach leaves and cook until completely wilted, about 3-4 minutes.
Remove from heat and let cool slightly.
Transfer mixture to a blender along with fresh coriander leaves.
Blend until completely smooth and silky in texture.
Return to pan and reheat gently before serving. Season with salt to taste.