Is it possible to cook meat using starlight and multiple magnifying instruments So you can burn a piece of paper with magnifying glass and sunlight. 
Light from stars are similar to that emitted by the sun, just much, much weaker. 
Theoretically, is it possible to cook a thinly sliced piece of meat using powerful magnifying instruments such as gigantic converging lens or dish or combination of those to converge light (and thus, energy) from stars? 
This does not have to be on earth, it could be carried out in space for example so there is less interference from external factors such as clouds etc.
If it can not be done, what is the limiting factor?
 A: Purely in theory, yes you could.
You don't really need the light to be of a specific wavelength to generate heat. You mostly just need a high enough concentration of photons.
The problem is that the number of photons falling on earth from a star is many times lower than that from the sun, so you'd have to concentrate the energy from an immense area to get the same intensity. 
Ignoring, for the moment, the filtering from the earth's atmosphere (and such), we receive about 1021 photons per square meter per second from the sun. The brightest star (other than the sun) is Sirius. We receive about 109 photons per square meter per second from Sirius, so we'd need to magnify by a factor of about 1012 just to match the intensity we reach from the sun without any magnification1.
Doing a bit of quick math, that works out to a single round magnifier about 10 kilometers in diameter, or equal area in other forms.
Then figure that cooking meat with sunlight does require at least some sort of magnifier, so we can probably multiply that by a factor of at least 3, and probably more like 7-10 or so.
Of course, for now I'm ignoring a such minor details as how you even design (not to mention building) a system even close to that size. There would be decidedly non-trivial challenges involved. For example, the largest mirrors we've built yet have diameters around 10 meters (or non-round mirrors of roughly equivalent area). These are already built in sections, with a computer to control movement of the individual pieces to maintain the illusion of a single mirror acting as a unit. Trying to multiply that out to multiple kilometers--well, I don't think anybody's even contemplated what that would take yet.


1. side note: both these numbers are really for the number of photons hitting the top of the atmosphere, not what we see on earth after being filtered by the atmosphere. We don't really care a whole lot about that though--the intent is just to get at least some idea of what it takes to concentrate starlight to approximately match sunlight.

A: In fact weaker light does not contain photons with less energy, it contains less photons. Which means that the heating and the ionising effect (aka burning) will be the same, just slower. So you could just leave your meat in space for a really long time and eventually it would be burnt. Or if you are not very hungry you can have a really really tiny "piece of meat", like a single atom, it might not take so long. 
Cosmic ray ionisation is a real problem/effect both in space and on the surface of the earth, especially for semi-conductor electronics in which it can cause data corruption, a bit-flip. Satellites have to be built with measures to protect against such corruption, either through shielding or detecting it.
A: Back in the days of Kepler, the theory was, that if sum of the combined light from all visible to the naked eye stars, approximately 5-10,000 max, was equal to or greater than, that received from the Sun. Then we would live in permanent daylight. This theory is still true today!
It would be possible to cook some meat in sunlight. If you live in a desert, just pop a black skillet in the sun and wait couple of hours, this would store enough energy from the sun to fry a egg, albeit slowly, because you need about 160°C to start frying anything, although 55°C is about enough for a rare steak. Now try the same thing under a full moon, it won't work, why? Because the moon only reflects the shorter wavelengths of light and not the infra red wavelengths, which it absorbs, and it is the infra red energy that you need to cook. By the time starlight actually reaches us, all the infra red radiation has been absorbed by interstellar dust or hydrogen molecules.
Therefore, the answer to you question would a be definite NO! No matter how many or how big your optical lenses were!
Another point is, that if infra red radiation from stars were actually reaching us on Earth, there would be a lot of amateur and professional astronomers with burnt retinas.
