Bring water to a near simmer a medium saucepan and remove from heat. Place the nuts in the water and steep for 2 hours on the counter.
Strain, reserving the liquid, and finely chop the nuts. Place the nuts on a square of cheesecloth, tying the corners together to form a bag. Place the bag in the reserved liquid, cover and let stand for 2 hours.
Remove the bag and squeeze to remove as much liquid as possible. Return the bag to the liquid and let stand for 8 hours more, squeezing every 2 hours.
Strain the liquid, discarding any solids. Weight the liquid and add an equal amount of sugar, gram for gram (or ounce for ounce).
Pour into a medium saucepan and add the salt. Over a low heat stir until all the sugar has dissolved. Remove from the heat, let cool and stir in the vodka and green coloring. Bottle and store in the refrigerator.