Using a food processor or blender, grind the almonds finely, then add the water and continue to grind until almost complete liquefied. Over a bowl, strain the liquid through a sieve lined with muslin or several layers of cheesecloth. When most of the milk has drained, gather up the edges of the cloth and squeeze the remaining pulp to extract as much liquid as possible. Discard the pulp.

Pour the liquid into a heavy saucepan, then stir in the sugar. Bring to a boil, stirring constantly, then lower the heat and simmer very gently for 5-10 minutes. Turn off the heat, add the orange flower water, and let the syrup cool. To serve, pour 1/4 cup of syrup into a glass, add ice water and stir well.