1. Boil water in a saucepan. Preheat the oven to 200 degrees. Press or mince the garlic. Finely chop the onion. Peel and dice the pepper. Peel the cucumber and cut it in half lengthwise, remove the seeds with a spoon and cut it into slices.
2. Heat a frying pan over high heat, then toast the pumpkin seeds until they pop. Set them aside out of the pan.
3. Place the baguette in the oven for 6 to 8 minutes or until golden brown. In a blender or mixer, add the pepper, cucumber, tomato sauce, 2/3 of the basil, garlic and onion. Blend for about 2 minutes to obtain a liquid soup. Add half a tablespoon of truffle balsamic vinegar per person and blend again for a few seconds. Add the olive oil, salt and pepper. Leave in the fridge before serving.
4. Before serving, prepare the vinaigrette by mixing half a tablespoon of truffle olive oil and half a tablespoon of truffle balsamic vinegar per person. Add the arugula and mix. Season with salt and pepper. Cut the baguette into 1 cm thick slices, then spread them with tapenade. Add a little truffle olive oil.
5. Arrange the gazpacho in a deep plate, season with salt and pepper. Add a little truffle olive oil. Add the pumpkin seeds and add the basil leaves. Arrange the salad and truffle tapenade toasts on the side.