A new McDonald's sandwich dubbed the 'millennial burger' has sparked a wave of cynical responses online which hit a little too close to home on what it's like to be a millennial.

The company started offering burgers and sandwiches with a Sriracha Big Mac sauce and kale this summer - two ingredients which have a cult following among millennials.

But some young internet users have pondered whether a real millennial burger would instead be filled with "emotional exhaustion, avocado toast, and front-facing cameras".

Sriracha is an Asian-born, American-made spicy sensation which has spawned a wave of imitators.

The original Huy Fong brand - now widely imitated - started out creating the low-key spicy-sweet product that could be used to spice up any dish, and ended up so mainstream that sriracha-themed products are sold on Etsy.

The brand was started in 1980 by a Vietnamese immigrant called David Tran. (Huy Fong is the name of the boat which took him to America.) The name is a tweak on Si Racha, a coastal town in Thailand famous for its red chilli sauce.

It was a mild success until the mid-2000s, when hipster and foodie culture boomed and fans of the sauce helped the hot sauce market to boom.

Meanwhile Google Trends shows that interest in kale has steadily rose over the past 10 years, levelling out over the past four years or so.

Avocado toast is another millennial food staple (Astrid Stawiarz/Getty)

The new McDonalds burger is currently only available in the US as part of the Signature Crafted Menu sandwich range and costs $5. It also includes spinach - a very 'in' superfood - along with onion, white cheddar, and tomato.

But since being dubbed the 'millennial burger', some cheeky social media users have responded with a list of things that burger should have contained to justify the moniker: and some are a litte too real.

"Never had a burger with 'being content with yourself and not emotionally exhausted in an age of social media', excited to taste," wrote Nikhil Krishnan.

"Remarkable how they got avocado toast AND being unable to afford a mortgage payment onto a single burger," added Jimmy Geurts.