Blanch the almonds in boiling water for 1 minute, then drain and pat dry with a towel.

Thread a large needle with a 30 cm length of cotton string. Push the needle through the center of each almond, leaving 20 cm of bare string at each end to tie into a loop. Repeat until you have 6 to 8 strings, spacing the almonds about 1 cm apart.

Rinse the grapes and pull them from the stems. Crush them by hand or in batches in a blender, then press through a fine sieve or cheesecloth into a bowl. You need about 1 liter of clear juice. Skip this step if using bottled juice.

Pour the juice into a 24 cm / 9.5-inch pot with the cinnamon stick if using. Bring to a gentle boil over medium heat and simmer for 15 minutes, skimming off any foam that rises to the top.

Whisk the flour with the cold water in a small bowl until smooth with no lumps. Pour this slowly into the simmering juice while whisking constantly.

Cook for 8 to 10 minutes, stirring often, until the must thickens enough to coat the back of a spoon and holds a line when you drag a spoon through it. Remove from heat and discard the cinnamon stick.

Let the must cool for about 15 minutes, until it's warm to the touch but not hot. If it's too hot it will slide off the almonds instead of sticking, and if it's too thin, boil it another 2 to 3 minutes before you try again.

Dip each string of almonds into the warm must, turning it so the coating is even, then hang it over a dowel or rod set over a tray to catch drips. Let dry for 3 to 4 hours, until the coating feels tacky rather than wet.

Dip each string again and let dry, repeating this 5 to 7 times over 2 to 3 days. Each string should slowly grow into a thick, sausage-shaped candy about 3 to 4 cm across.

Once you're happy with the thickness, hang the strings in a cool, dry spot away from direct sun for 2 to 3 more days, until the outside feels firm and slightly matte but the inside still gives when you press it.

Slice the soutzoukos into rounds and serve at room temperature.