Hang around Facebook and Pinterest long enough and you’ll see them: Hacks. Substitutions. Crazy new uses for ingredients that sound just crazy enough to work — or just plain crazy.

Some of these things aren’t new. Using mayonnaise to replace eggs in cakes started with food rationing in World War II (yes, your grandmother knew that trick). Others, like using the liquid from cooked beans to replace egg whites, are so new, you’d expect Jane Jetson to do the video demo.

There’s a fine line between brilliant and bust in the kitchen. Recently, I rounded up five of the most bizarre ideas and gave each of them a try. Which ones passed … and which one failed?

1. Mayonnaise. Grade: A+.

Mayonnaise chocolate cake from a mix: It doesn’t save using eggs, so why bother? Here’s why: Because cake mixes with pudding added (and that’s pretty much all of them now) make gummy cakes. Instead, trying skipping the oil and using 1 cup mayonnaise along with the usual 1 cup water and 3 eggs. Then follow the rest of the directions. You’ll get a moist, tender cake.

Mayonnaise chocolate frosting: Yes, it sounds “ew.” But it’s tangy, like a chocolate sour cream frosting, with a fluffy, spreadable texture. And it’s two-ingredient easy: Melt 2 cups semisweet chocolate morsels over low heat. Remove from heat and cool about 5 minutes. Whisk in 2/3 cup mayonnaise. Use to frost a cooled 13-by-9-inch cake or a dozen cupcakes.

2. Avocado. Grade: A.

Avocado chocolate mousse: It replaces dairy products, and it’s much simpler. (See recipe).

Avocado chocolate shake: If you put frozen spinach in your breakfast smoothie, is an avocado in your chocolate “shake” all that strange? You get creaminess without all those ice cream calories. Combine 1 1/2 cups nonfat milk, 1/2 of a ripe avocado, 2 tablespoons each brown sugar and cocoa and 1 teaspoon vanilla in a blender and blend until smooth. Serve over ice. (From Prevention.com.)

3. Bean water (aka aquafaba), the juice from canned or cooked garbanzo or white beans. Grade: A-.

Aquafaba mayonnaise: If you’re vegan, egg-allergic or averse to separating eggs, this stuff can be amazing: 3 tablespoons of the liquid from cooked beans equals a single egg white. To make mayonnaise, use a blender or immersion blender to combine 3 tablespoons bean cooking liquid, 2 teaspoons lemon juice and 1 teaspoon apple cider vinegar until white. Slowly drizzle in 1/2 cup vegetable oil while blending. Taste and add salt if needed. (It depends on how salty the canned beans are.) It isn’t quite as stiff as egg-based mayonnaise, but it’s definitely workable.

Aquafaba Ramos gin fizz: It’s a classic among cocktails, with a frothy top. But who wants to separate an egg white at their home bar (and what do you do with all those leftover yolks)? Instead, combine 3 tablespoons bean liquid, 2 ounces gin, a few drops of orange blossom water (or Regan’s orange bitters), 1 tablespoon each fresh lemon juice, fresh lime juice, simple syrup and half-and-half in a cocktail shaker with ice. Shake vigorously for 30 seconds or so. Use a wide strainer to strain into a tall highball glass.

4. Sweet potatoes. Grade: B-.

Sweet potato chocolate frosting: Starting with Food52, this is all over the internet now as a replacement for canned frosting. Yes, it’s fluffy and swirly, but the flavor is disconcerting. It helps if you add vanilla and cinnamon, but it’s still odd. Empty 1 (15-ounce) can sweet potato puree (not pie filling) into a medium saucepan and heat through. Remove from heat and add 10 ounces (1 2/3 cups) chopped bittersweet chocolate, 1/2 teaspoon vanilla and 1/4 teaspoon ground cinnamon. Stir until melted. Let stand about 30 minutes, stirring every 10 minutes, until completely cool.

Sweet potato caramel: This one started with Bon Appetit, and it is delicious. It only makes about 1/4 cup, though. If you’re roasting sweet potatoes anyway, it’s worth a try as a glaze for pork or roasted vegetables, and you can add a little sugar to make it into an interesting dessert sauce. See recipe.

5. Sauerkraut. Grade: F.

Sauerkraut macaroons and German chocolate cake: This has been around since World War II, when it started as a replacement for coconut. No matter how well we rinsed it and squeezed it dry, though, it definitely didn’t work in macaroons, unless you like cookies that taste like a swamp. In a chocolate cake, the flavor is harder to detect, but it’s still too chewy with an odd taste. Besides, if you have to go to a store to buy sauerkraut, why not just buy coconut?

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VEGAN CHOCOLATE MOUSSE

Adapted from “It’s All Easy,” by Gwyneth Paltrow.

1 large avocado, pitted and peeled

2 tablespoons almond butter

Sea salt

1/4 teaspoon vanilla

1/4 cup brown rice syrup

1/4 cup maple syrup

1/4 cup raw cacao or unsweetened Dutch-processed cocoa

1/4 cup almond milk

2 tablespoons coconut oil

In a blender or food processor, combine all the ingredients. Blend for 2 minutes or until very smooth. Divide among 4 ramekins and refrigerate at least 1 hour.

Yield: 4 servings.

SWEET POTATO CARAMEL

From Bon Appetit.com

3 pounds sweet potatoes, peeled and cut into quarters

1 cup water

Preheat heat oven to 425 degrees. Place chopped potatoes and 1/2 cup of water into a 13-by-9-inch baking dish, covered with foil. Bake for 1 hour. Uncover and bake 15 minutes longer. Remove dish from oven and add remaining 1/2 cup of water to loosen up any bits in the baking dish.

Place all the solids and liquids into a strainer lined with cheesecloth. Let drain into a saucepan and cool for 30 minutes. Once cool enough to handle, squeeze as much liquid out from the potatoes in cheesecloth as possible. You should end up with about 1 1/2 cups of liquid.

In a saucepan, bring the sweet-potato liquid to a boil, then reduce heat for a steady simmer. Allow the liquid to reduce for 15–20 minutes until it starts to thicken and starts to form a caramel; stir often in the final minutes. Pour into a jar and store in the refrigerator for up to 2 weeks. (You can also add about 1 tablespoon of sugar to make it more of a dessert caramel.)

Can be served with roasted meats or as a sauce over ice cream or brownies.

Yield: About 1/4 cup