Place on eggplant on the flame of a gas stove directly. Keep turning the sides until the skin is charred all over. Do not overdo this because we want to chop the flesh later and not mash it - so the eggplant should still be able to keep its shape somewhat. Once this cools, peel off the skin and roughly chop this into cubes. Keep aside. This will be used towards the end as it needs no further cooking.

Chop the other eggplant into small cubes with the skin on. Keep aside.

In a large pot, heat olive oil and throw in the minced garlic. After a few seconds, add the chopped spring onions. Saute for 3-4 minutes, until wilted.

Add the chopped raw eggplant first, sprinkle salt and saute along with the garlic and greens. After 3-4 minutes, keep this covered for 5 minutes or so until the vegetable is almost cooked. Add the tomatoes, herbs, chilli flakes balsamic vinegar and on a medium flame let this cook till tomatoes soften down and the vegetables come together.

Add remaining salt, chopped roasted eggplant and fresh basil. Toss well and check for salt and chilli, adding some more if you prefer so.

To assemble the sub, slice the hot dog roll in the middle, but keeping the two slices attached. Spoon a generous quantity of caponata between the two, stuffing it tightly. Also stuff in a couple of slices of tomato or pickled jalapeno and some bits of sliced cheese and grill on a hot buttered skillet or in a hot oven till crispy outside.