Preheat oven to 375 F. Line a baking sheet with parchment paper.
In a bowl toss the diced bread with olive oil and a pinch each of salt and pepper until well coated. Spread out onto the baking sheet.
Bake until golden, turning once half way through – about 15- 20 minutes. Remove from oven and allow to cool completely.
Meanwhile, in a bowl, whisk together the garlic, Dijon, lemon juice, olive oil and a pinch each of salt and pepper, to taste.
To serve, toss the croutons with the tomatoes, avocado, cucumber and canned tuna. Drizzle with the olive oil, and top with hemp hearts, pistachios and basil.