To make simple syrup, place sugar, thyme sprigs and 1 cup water in a small saucepan and heat, stirring often, until sugar is dissolved.
When sugar has dissolved, remove pan from heat and let cool. Once cool, discard thyme sprigs.
To make lemonade, combine the simple syrup with remaining ingredients, except vodka, in a pitcher and place in refrigerator to cool.
When ready to serve, pour into glasses filled with ice, add a splash (1-½ oz) of vodka, if using, then garnish with a slice of lemon, a strawberry and a sprig of thyme.
Notes
Nutrition facts are for the non-alcoholic version. Add 98 calories per serving if adding vodka.