Before you begin assembling the drink, place a champagne flute in your refrigerator, so that it can chill and become nice and frosted. Meanwhile, take a cocktail mixing glass and wash it thoroughly – this will be the vessel in which you will be making the drink.
Place the mixing glass on a flat counter space, and add in 1/2 an oz of triple sec, 1 1/2 oz of fresh orange juice, and 3 1/2 oz of chilled champagne. Use your spoon to stir the liquors together, until they have all been mixed thoroughly.
Once the cocktail has been mixed, place the mixing glass containing the Mimosa cocktail in the refrigerator – this needs to be chilled thoroughly, and you cannot add ice cubes to the mix, or run it through a cocktail shaker loaded with ice.
After the cocktail has been chilled through, take the chilled champagne flute out of the refrigerator, and pour the Mimosa cocktail into this. There are a variety of options for garnishing the drink – the most common is to stick an orange wedge onto the rim of the glass, but you can also substitute this with a lemon slice, or float two or three large green mint leaves on the top of your drink. Your Mimosa cocktail is now ready to serve.