Since Buddhists believe in Emptiness, not Being, how do they explain how something can come from nothing?

Buddha does not attempt to explain anything. He simply is there to help you to awaken and experience 'what is'.

Complete misunderstanding what "emptiness" means. I really hate that all the Buddhist core terms have an English translation. It leads to such harmful misunderstandings. You assume you know what is meant bc. you think you know the word.... but of course you don't have the slightest inkling. What is meant by Shunyata is that there is no intrinsic self. This is an EXPERIENCE (verifiable for ppl that can be bothered) that grows out of meditation practice. Sorry, but I'm not really qualified to talk too much about this. If you are genuinely interested (and the form of your question suggests that you are not), there are many books and forums or teachers to ask that can put it better than I ever could. I don't want to mess up someone that reads this with an unexact explanation.

Show me this "reality" you speak of.

Buddha specifically teaches the opposite- that all conditioned phenomena (in regards to our experience/mind) is dependently arisen based on its requisite. By removing the requisite cause, the condition for stress cannot be sustained. The Buddha taught that all of experience, throughout every life you've lived, is based on twelve links of causally bound phenomena. While linear in relation, Buddha taught that our minds are intertwined like a ball of string. The chain goes two ways: either perpetuated or cut. Whichever you engage in more will ultimately win. This is why whichever lifestyle you live with conquer. The path to material gain is one way, the path to unbinding is another. Aging and death have birth as its requisite. Birth has becoming as its requisite. Becoming has clinging as its requisite. Clinging has craving as it's requisite. Craving has feeling as its requisite. Feeling has contact as its requisite. Contact has six sense media as its requisite. Six sense media has Name and form as its requisite. Name and form has Consciousness as its requisite. Consciousness has fabrications as its requisite. Fabrications have ignorance as its requisite. Reversing the chain is in essence escape from samsaric existence through awakening. The Buddha said it is the not seeing or comprehending of this one doctrine that beings remain bound. The Buddha was fully awakened to the existential system and taught a causal exposition of mind and matter.

There's no something out there! Existence as we know it is all in our minds. By the way, there are examples of things coming from nowhere all the time. Like this answer.

This is a great question. Yes, Buddhists believe in emptiness, but we also believe/experience life. The two things together are what make up our daily life. Emptiness (aka space, openness, ground) is the canvas on which the events of life happen. Without space, you can't have experience - there would be no room, everything would be solid and immovable. But without the "something" from your question, we wouldn't exist. That doesn't work. So the two things are "co-emergent". In other words, they rely on each other. Without the seagull or the clouds, we wouldn't see the space around it. Without the space, the seagull couldn't fly. Importantly, this approach to how the world works does not require a god or some other being to create it. Creation myths don't work well in Buddhist philosophy.

You seem to me to be trying to reduce the vast, magnificent, untamable wonder that is reality, and make it small, simple, logical, and easily comprehended by our tiny human minds. If you've reduced life to the point where you can understand it, then you're missing most of it.

No answer ("Nothing") was created prior to this question. But after the invention of internet, server, hard disk, Quora.... And most importantly is your curiosity mind and posting of this question into Quora. Then it gave the opportunity to us to add our opinion here. Therefore, something is created if given the right mixture of conditions. However, this "thing" is impernance, it may disappear due to corruption of data, failure in Quora and etc. Eventually it goes back to the state of nothing.

Emptiness is where things arise from and return to. Listen.  Now say a word.  One can only hear against a background of silence. The word arises from silence and returns. Tap the surface of your laptop.  Without space, there would be no surface, no laptop, just immobile matter as if you were buried. Black and white together, make the whole.