While the paneer grills, dice the onion or slice it into crescents. If you intend to use an immersion blender on the sauce in Step 5, then you can chop the onion coarsely instead. Mince/press the garlic, and grate the ginger.
Heat the vegetable oil in a large pot over medium heat, then add the onion and stir occasionally and cook until light golden, about 8-10 minutes.
Add garlic, ginger, tomato paste and garam masala to the onion. Stir constantly until well-combined and fragrant, about 1 minute.
Add crushed tomatoes, agave, and salt, then bring to boil. Reduce heat to medium-low, cover and simmer for 15 minutes, stirring occasionally.
Remove the pot from heat. Stir in the cream. If you prefer a smoother sauce, use an immersion blender until you like the consistency. Cover the pot to keep it warm.
Once the paneer is done, stir it into the sauce.