1 Cut ciabatta into slices, about 1 cm (approximately 3/8 inch) thick. Place slices directly on oven rack and toast in preheated oven at 200°C (fan: 180°C, gas: mark 3) (approximately 400°F) until golden. Let cool slightly.
2 Halve avocado lengthwise and remove pit.
3 Scoop avocado out of the shell with a spoon into a deep bowl.
4 Squeeze juice from lemon. Peel garlic and coarsely chop. Crumble goat cheese. Add cheese, 2 teaspoons lemon juice and garlic to avocado. Puree with an immersion blender. Season with salt, pepper and additional lemon juice, if desired.
5 Rinse tomatoes, drain and cut into quarters.
6 Spread pureed avocado-cheese mixture on ciabatta slices and top with tomato quarters. Rinse chives, shake dry, snip into pieces and sprinkle over the crostini. Serve immediately.