Shrimp Salad with Lemon Juice

1/2 pound jumbo gulf shrimp (boiled with shells on in large pot of salty water for 45 seconds, then chilled in cold water. When chilled remove peel)

1/2 bunch celery, chopped against the grain.

1 large ripe tomato, seeded and diced into 2/3-inch cubes

1 large shallot, diced into 1/4-inch cubes

1/2 bunch cilantro leaves, roughly chopped

Sea salt and freshly ground black pepper

Olive oil

2 ripe lemons, juiced

1 ripe avocado diced into 1/2-inch cubes

1/2 can mandarin oranges