Frozen berries and vegetables are one way to get the vegetables and fruits you need. I'm not sure of their impact on the environment, and so am going to read more about that and report back.
What I do know is that they generally freeze the vegetables and fruits extremely quickly, and at the time when they are most nutritious. Let me know if you have insights.
Here's one way to enjoy berries in winter:
Ingredients (around 300 calories/serving, which is 1/12 of the total round pan)
3 cups mixed frozen berries
2-3 tablespoons of white sugar
4/3 cups flour
4/3 cups oats
1 cup brown sugar
cinnamon and nutmeg, about 1 tsp
1 cup butter
Note: You can also reduce the sugar and butter by using honey.
Place the frozen berries aside to thaw..
Combine the dry ingredients, then gradually cut in small bits of butter until the butter and dry ingredients make a crumbly mixture.
Place 1/2 the crumbly mixture in the bottom of the circular pan. Put the berries on top, and then put a second layer of crumbs on top. (see below.)
Bake in pre-heated oven at 350 F for 40 minutes, or until the berry mixture is bubbling up.