We have a Sunday night ritual at our house that involves me not cooking dinner. We usually eat a pretty big lunch that day so we tend to do easier things for dinner. During the warm time of the year that usually means smoothies. We'll combine smoothies with popcorn, grilled cheese or peanut butter sandwiches, etc. for an easy meal. I have a smoothie book that I love, but can't find a lot of the specific ingredients here so we improvise a lot. But, they always turn out really well. Here's what we made last night:
4 frozen bananas
2 c. frozen strawberries
1 c. frozen blueberries
3 small containers of yogurt (blueberry, strawberry, and pineapple)
1/2 to 1 c. plain yogurt
3 T. flaxseed (lino semi), ground fine in a coffee grinder
2 T. crusca di grano (wheat germ)
Put all that in a blender and blend until smooth and you see the vortex in the blender.
My original "nanaberry shake" recipe that I follow has:
1 c. milk
2/3 c. apple juice
1 t. vanilla
2 frozen bananas
6 large frozen strawberries
6-10 ice cubes
Bottom line, I think you really can't go wrong with smoothies. I rarely keep plain ice cubes so I often throw in one or two extra frozen bananas. Sometimes I splurge and throw in some gelato. Sometimes I use juice. Any kind of frozen fruit works. And if I want it to have a little caffeine, I've used black tea ice cubes to make black tea smoothies with lots of frozen fruit.
NOTE: I do think it takes a fairly strong blender to handle all the frozen fruit and/or ice cubes. I burned up one inexpensive blender our first year here. But, my bosch has handled it all really well for the last 3 or 4 years.

