Using a "muddling" stick or small wooden spoon, mash strawberries, jalapeno and lime in a cocktail shaker until the berries are broken down. Add liquor, Grand Marnier and agave (or simple syrup). Fill the shaker with ice; shake well. Taste and add more jalapeno and/or agave, if desired. Strain into 2 martini glasses. Garnish with a strawberry and a jalapeno slice.