3 healthy lunches that anyone can make for less than $7

Buying your lunch has its advantages. You can get some fresh air and skip the frantic meal prep the night before.

But the daily habit could be costing you thousands of dollars each year, and you're most likely consuming a lot of salt and other ingredients.

"Eating out in general and the cost of labor that goes into that food, it certainly adds up," chef Jason Roberts tells CNBC Make It.

Buying food and cooking it yourself is a lot better for your wallet, and your well-being, he says.

Roberts, who has worked with singer Pink, actors Keanu Reeves, Jeff Bridges and others, says that making even just a few meals for yourself each week will help you save money and feel more energized.

Here are three easy lunch recipes from his new book "Good Food Fast," that cost under $7 per serving:

"This is a great alternative to something slapped between two pieces of bread," says the chef, who splits his time between Australia and the U.S. "It has plenty of flavor and texture and there is definitely room for you to add your own flair."

Ingredients:

2 cups baby spinach or arugula leaves

½ a small butternut squash, peeled and seeds removed

1 cup cooked lentils

1 small bulb of fennel or other raw vegetable like celery, carrot or celery root, thinly sliced

2 tablespoons olive oil

¼ teaspoon cracked black pepper, plus more to taste

1 teaspoon fennel seeds

½ tspn dried chilli flakes (optional)

¼ cup almonds roughly chopped (toasted for extra flavor)

Salt, to taste

Juice of ½ a lemon

Directions:

Pre-heat the oven to 400F

Dice the squash into large or medium pieces and place into a bowl. Add olive oil, spices and a good sprinkling of salt. Gently toss so the squash is evenly seasoned.

Place the squash onto a baking sheet lined with parchment paper and place into the oven.

Bake for approximately 15 to 20 minutes. The squash should be golden, caramelized and tender. Remove from heat when ready and allow to cool.

In a separate bowl, mix the olive oil, juice from half a lemon, salt and pepper. Then add the lentils, roasted pumpkin, fennel or other raw vegetable, almonds and spinach. Toss the ingredients.

Put into a reusable container and enjoy the next day.

"In my mind," Roberts says, "the taco is the ultimate way to use up leftovers."

Ingredients:

A couple of thick avocado slices

¼ cup shredded roasted chicken (If you're pressed for time, you can use pre-cooked chicken strips)

Jalapeno pepper, finely chopped, to taste

A couple whole cilantro leaves

¼ lime, squeezed over the taco to finish

1 tortilla (Gluten-free is what Roberts suggests, though any kind will do)

Directions:

Add the ingredients to your taco and put in a reusable container.

"I like to think of [the tortilla] as a blank canvas that I paint on with a variety of delicious elements," the chef says.

"This a great salad by itself or served alongside a piece of chicken, pork or even cold-cut meat," he says.

Ingredients:

5 small red beetroots (beets)

Salt and freshly ground black pepper, to taste

1 small bulb of celeriac (If celeriac isn't available, try another one cup of chopped cabbage or carrots)

Juice of 1/2 lemon

1 ½ tbs mayonnaise

1 tspn Dijon mustard

1 orange, sliced or segmented

¼ cup toasted walnut halves

½ cup of fresh mint leaves

Beet chips (optional)

Directions:

To prepare the beets for roasting, scrub them under cold running water to remove any dirt. Then, after drying, sprinkle with a little oil and season with salt and pepper.

Wrap each beetroot individually in foil and roast in a preheated oven (375 to 400F) for around 30 minutes. To test if ready, push a skewer into the larger of the beetroots, there should be no resistance. Remove from oven and cool. Feel free to peel away skin, however it's not necessary if scrubbed well, Roberts says.

Next, peel the skin from the celeriac bulb (or alternate vegetable) and then slice into small rounds. Then slice lengthwise into thin julienne strips and toss in lemon juice to prevent browning. Combine the celeriac (or alternative vegetable) with the mayonnaise and mustard, mix well.

To serve place the beets in with the celeriac or alternate vegetable and toss very gently. Then scatter the mint leaves and orange segments on top.

"You can have good food that you made fast," Roberts says. "It gives your body so much more energy."

Check out 5 healthy foods to help you kick your vending machine habit and boost productivity

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