Infuse the vodka (about 3-4 days in advance of your float)
Hull and slice the strawberries. Place strawberries in the jar and pour enough vodka to cover the strawberries.
Seal with a tight fitting lid and store the jar in a cool dark place for 5 days and up to a week, giving it a daily dose of agitation (shake it, baby). Strain the mixture over a strainer lined with a coffee filter or cheesecloth taking care to squeeze the strawberries to extract all the liquor. Pour into 2 one cup jars and cover with a lid. Makes about 2 cups of strawberry flavored vodka.
Macerate your strawberries:
Place the strawberries in a small bowl and sprinkle the sugar on top. Add the vanilla bean paste (if using) and stir until combined. Stir the strawberries occasionally until the berries are juicy, 30 minutes to 1 hour.
Make the strawberry syrup:
Combine the strawberries, water, sugar, and vanilla extract in a small pot. Bring to a boil over high heat. Lower the heat and simmer until the sugar is completely dissolved and the strawberries have and softened, about 15 minutes. Remove from heat and strain the mixture, pressing on the solids to extract as much liquid as possible. Discard the solids or save them for another use. Syrup will keep in the refrigerator for about a month and can be used for sodas and other boozy drink situations.
Build your float:
To an 8 ounce glass add the strawberry syrup, followed by 1 tablespoon of macerated strawberries. Add your strawberry vodka and stir to combine. Add a couple of scoops of ice cream, followed by the remaining macerated berries. Top with seltzer and another scoop of ice cream, if desired.Garnish with strawberries if you want your jam to look pretty.
Vodka, macerated strawberries, and syrup makes at least 4 floats.