The ingredients were:
I started with about a half-cup of milk, then the banana and a teaspoon of vanilla. Then I blended it with my handy stick blender until it was smooth and thick and frothy. If it was too thick (since bananas vary in size) I added more milk to make it drinkable.
As I explained to people, you can adjust it to your liking, depending on whether it's supposed to be a hearty drink or something you're sipping through a straw. If people wanted strawberries, I added one frozen strawberry to the basic combo and that was enough to turn it a lovely pink and add just enough strawberry taste without obliterating the banana flavor.
The one ingredient that people commented about most often was the vanilla. Although a lot of the folks made smoothies for themselves, few had considered adding vanilla, and it really does add a nice flavor to the drink.
I also noted that keeping the bananas in the freezer would result in a colder drink without the need to water it down with ice.
And of course the milk could be any type of milk, depending on what people liked.
So here come the options.
For the milk portion, use:
Whole milk, 2%, 1% or skim
Any of the above could be flavored or plain
I probably forgot something, but any milk or milk-like dairy or nondairy beverage would be just fine.
If you don't like dairy products, then any fruit juice would be fine, as well.
Optional add-ins include:
Any fresh or frozen blendable* fruit. almond extract or other flavorings or extracts, nutmeg, ginger, chocolate syrup or cocoa powder, protein or dietary fiber powder, nutritional yeast, tofu, ricotta, peanut butter or other nut butters, applesauce, or pumpkin puree. Fruit juices and nectars and vegetable purees and juices would also be good, as long as the flavors matched. If you want more sweetness you could add any sort of jam, jelly or fruit spread; honey, agave nectar, or maple syrup..
*Since I was using a stick blender, I was limited to fruits that the stick blender could handle, but if you're using a regular blender that can handle harder fruits, you have even more options.
Really, it's all about what flavors you like. If you don't like bananas, use any other fruit that makes you happy. Keep it simple, or go crasy with mixtures. It's your drink, you don't need a recipe.
Besides flavors, there's also texture to consider. A smoothie should be thick enough to be satisfying but thin enough to drink. If you use a lot of thick ingredients like banana, peanut butter, and tofu, make sure to thin it out with milk or juice or you'll need a spoon for your smoothie. If you use fruit juices and watery whole fruits, make sure you include something to give it some body or you'll end up with fruit juice instead of a smoothie.
Above all, make something you like, whether it's think, thin, creamy, fluffy, fruity, sweet or savory. Make it heathy or make it decadent. But please, make it tasty.