Hull and slice the strawberries. You can simply cut off their green tops, but cutting those tops and the white flesh just underneath yields a prettier, heart-shaped slice. To hull the berries, insert the tip of a paring knife in and under the green stem and turn the strawberry so the knife cuts out the hull, or calyx.
Put the sliced strawberries, the juice of 2 of the limes, the sugar, and the gin or vodka in a pitcher. Stir to dissolve the sugar.
Let the mixture sit about 1 hour if you can. This sitting time lets the alcohol pull flavor out of the strawberries and will give the final sangria a deeper, more fully strawberry taste.
Pour in the wine.
Scrub the final lime clean, thinly slice it, and add it to the pitcher.
Roll the mint leaves in your hands to release their fragrance. Stack them and use a sharp knife to cut them into thin strips; add the mint to the pitcher.
Pour into glasses full of ice. For a lighter drink, use half sangria and half seltzer.