Soak the stale white bread slices in water for a few minutes until they become soft. Squeeze out excess water and set the bread aside.
In a bowl, place the fish roe (tarama).
In a food processor or blender, add the soaked bread, minced garlic, chopped onion, lemon juice, and water. Blend until you achieve a smooth mixture.
Add the blended mixture to the bowl of fish roe (tarama) and gently fold and mix until well combined.
Slowly drizzle the extra virgin olive oil into the taramosalata mixture while continuously whisking or stirring.
Taste the taramosalata and season with salt and pepper to your preference. Adjust the seasoning accordingly.
Transfer the prepared taramosalata to a serving dish or container, cover, and refrigerate for at least 1-2 hours to allow the flavours to meld together.
When ready to serve, garnish with a drizzle of olive oil, thinly sliced red onions, and Kalamata olives.
Serve chilled with warm pita bread, fresh vegetables, or as a spread on sandwiches or wraps.