Slice avocados in half, remove pits, and cut flesh into quarter-inch slices while still in the skin for easy removal.

Halve cherry tomatoes, thinly slice red onion, and dice cucumber with skin on; set aside.

Preheat oven to 375°F (190°C) and spread bread cubes on a baking sheet; toast for 5 to 7 minutes until golden, or heat a dry skillet over medium and toast cubes for about 4 minutes.

In a small bowl, whisk olive oil, lime juice, and Dijon mustard until emulsified into a pale, creamy dressing.

Place cooked shrimp in a bowl and gently toss with half of the vinaigrette and a pinch of sea salt.

Combine tomatoes, cucumber, red onion, and cilantro in a large mixing bowl; drizzle with remaining vinaigrette, season with salt and pepper, and gently toss.

Refrigerate shrimp, vegetable mix, and bread cubes for 5 to 10 minutes, and chill serving bowls and cava.

Divide chilled cava evenly among four bowls, filling each halfway.

Layer bowls with the vegetable mixture, top with dressed shrimp and avocado slices, scatter toasted bread cubes on top, and serve immediately.