Preheat the grill to medium heat.

In a small mixing bowl, combine olive oil, lemon juice, and chopped thyme.

Season the mixture with salt and pepper to taste.

Stir well to combine.

Season the fish fillets with salt and pepper.

Brush both sides of each fish fillet with the lemon-herb mixture.

Top each fillet with thin lemon slices and thyme sprigs.

Soak banana leaves in warm water to soften.

Lay two banana leaves in a cross shape.

Place a fish fillet in the center of the crossed leaves.

Wrap the fish completely in the banana leaves, creating a pouch.

Secure the banana leaf pouch with soaked toothpicks.

Place the fish pouches on the preheated grill.

Grill for 4 to 6 minutes on each side, or until the fish is cooked through.

While the fish is grilling, heat olive oil in a saute pan over medium heat.

Add the assorted fresh vegetables (cabbage, onion) to the hot oil.

Season the vegetables with salt and pepper to taste.

Saute the vegetables for 3 to 4 minutes, or until tender-crisp.

To serve, place a grilled fish pouch in the center of each plate.

Carefully remove the toothpicks and open the banana leaf to expose the fish.

Serve the sauteed vegetables around the fish.