Blueberries can't be beat. Other berries are great too, but the mighty blue is a powerhouse.

I honestly don't eat very many veggies - just not my thing. But what I've started doing is growing a variety of herbs like rosemary, thyme, oregano, mint and basil and having a mix of it (about a handful) with lunch. The nutrient content and phytonutrients of herbs are huge compared to lettuce and such. Oh, and they have so few calories I wouldn't bother counting them :).

I'm surprised no-one else has mentioned that low-carb powerhouse, spinach. Loads of potassium and magnesium (just what low-carbers need especially), vitamin C, beta-carotene, manganese, copper, selenium, iron e.t.c and also plenty of choline, betaine and the B vitamins necessary to neutralise the homocysteine engendered by a high methionine diet e.g. a meat rich diet. One of the very few omega 6 free foods with significant vitamin E.

If you are going for low carbs/high nutrients try nettles.

They are very high in calcium, magnesium and are high in iron, potassium, zinc, Vitamin B's and A; they supply niacin, protein, vitamin C, D and K. Nettle has 3 times more iron than spinach, 7 times more Vit C than oranges and have 35% protein on dried weight. Overall nettle is 3 times more nutrient dense than any cultivated green you can buy (and they are free).....

Here is a recipe for nettle pesto, or you can wilt the leaves over a flame to get rid of the sting and eat like spinach.

Parsley! Kale! Chard!

Blackberries, raspberries, strawberries, papaya (a bit higher in sugar) - these dudes are amazing for your bod. I want to support the furry Kiwi, too. Yes it's higher in natural sugar than some of the other fruits but the level of vitamins E - C - K, potassium, copper, the seeds carry an omega 3 fatty acid property, I'm only giving a few things, too!, make them an amazing occasional treat.

For veg I like heavy greens such as kale, spinach, turnip greens, dandelion, purslane, as I can eat them raw or cooked - the kale leaves are great to wrap around a burger as a "bun" to hold in your hands. Broccoli is another - broccoli kind of bugs me for some reason so I don't really buy it that often. Zucchini has fantastic health benefits, you're not going to eat a billion of them so the carb/sugar ratio isn't bad, and if you can get your hands on an avocado squash or a Zephyr zucchini - do it. So good, I make salads out of them, mandoline thinly, salt, some lemon juice, a bit of mint and prosciutto - tasty!, and add as the base to my frittatas. Happy eating!

Herbs: basil, rosemary, oregano, thyme, etc.

Spices: cinnamon, tumeric, cayenne pepper, cocoa (I consider pure unsweetened, naturally processed and/or raw cocoa a spice) etc.

Greens: dandelion, chard, spinach, kale, mustard, collards, beet, etc.

Low GI/GL Fruits: lemon/lime (for dressing and flavoring water), unsweetened acai puree (for smoothies), blackberries, tamarind (check out this post for more info about this amazing fruit), etc.

Purslane wins every time.