Cook the shrimp in fish stock until they turn pink.
Drain the shrimp and let them cool.
Once cooled, peel and chop them coarsely, then place them in a small bowl.
Chop the hard-boiled eggs and add them to the shrimp along with the celery, green onions, and parsley. Set aside.

Soak the gelatin in water for 5 minutes.
In a bowl, mix together the natural yogurt, mayonnaise, and Dijon mustard.
Add the gelatin, which has been previously melted for a few seconds in the microwave, and mix well.
Pour the preparation over the shrimp preparation and mix well.
Adjust the seasoning as needed.

Pour into molds lined with plastic wrap or silicone molds and refrigerate for at least 4 hours.
Serve on toasted bread slices and accompany with a salad.