How to cook delicious BBQ eggplant 🍆 barta

3 large eggplants 🍆
One onion
Half cup tomato paste
8-10 garlic cloves
Oil as required
Green chilli 2
Green green coriander as required
Salt to taste
Coriander powder 1 tbsps
Cumin seed 1/2 tsp
Turmeric powder 1/2 tsp
Red chilli powder 1/2-1 tsp