Slice each eggplant in half lengthwise. With a spoon remove the flesh from the center of the eggplant halves, leaving a ¼ inch rim around each. 100 g of the scooped out flesh chop in a food processor. Set aside.
Grease the scooped out aubergine halves inside and outside with 1 tablespoon of olive oil and season with salt. Place them on a large baking sheet lined with parchment paper and bake in the oven for 20 minutes at 200 ° Celsius Remove from the oven, set aside.
Sauté onion and garlic in 1 tablespoon olive oil, stirring occasionally, for 4-5 minutes until soft. Add the chopped eggplant flesh and continue to sauté for 5 minutes until the eggplant pieces are soft. If necessary, add a little water.
Add sliced green peppers, sauté for 5 minutes until tender.
Add tuna chunks and cooked bulgur. Break down larger tuna chunks, stir the mixture to combine.
Add thyme and basil leaves, sea salt, pepper and lemon zest, mix to combine.
Stuff evenly the scooped out eggplant halves with the tuna and bulgur mixture. Sprinkle with grated Grana Padano or Parmesan cheese and the remaining olive oil. Bake in the oven at 200°C for about 10 minutes until cheese becomes golden-brown.