Prepare a tin for your fudge to set in. I line a 20cm square cake tin with baking paper. The tin does not get baked so you can actually set your fudge in anything. Lining the tin means it is easy to lift out the fudge when it has cooled.
Place the sugar and water in a medium, heavy-based saucepan. Heat over medium heat until all the sugar crystals have dissolved.
Add the vegan butter, and heat until melted. Once melted add the salt and coconut condensed milk.
Increase the temperature until your fudge mixture comes to a boil. Boil for approximately 5 minutes you are aiming for a soft-ball stage (which is 115 degrees Celsius) Remove from the heat, and add half the lime zest or the vanilla extract
Remove from the heat, and add half the lime zest
Now it's time to beat the fudge. I use an electric beater and beat until the fudge is creamy and thick (it will almost be setting) and has lost its glossiness. It should now appear like it has a matt finish.
Pour into your prepared tin, sprinkle with the remaining lime zest and pop into the fridge until cool.
Slice into squares.