You want to make sure he def likes whatever you mix it with and then keep track of how much you put in (I wouldn't do the whole dose at a time unless you think he won't notice and is quite hungry). You still have to give the whole dose each day, but you have to track it in increments in case he throws part of it down-- you will have to get that replaced down the road (as you will need to use the meds you have to replace it at the time). It's very important to dose antibiotics correctly and always finish the course completely.
Plain baked sweet potatoes (eyes and skin removed) can work --roll into a ball and kind of mix meds in with them and (as you suggested) baby food, can also work. (healthy)
Oatmeal (plain) cooked with a mashed banana and some other fruit can work as well. (healthy)
The color of the meds can be huge to them, so whatever the color is, try to find something that can serve as a camo for it (without harming them)..obviously no artificial sweeteners, no avocado, chocolate, caffeine, garlic, onion etc...but a TINY bit of sugar or salt can be okay in moderation---they key is TINY- My bird is also a lot larger (umbrella cockatoo), and I broke her halves into 4ths in case she wasted them...you might need to do even less...and remember, sugar can feed a bacterial infection, so consult your vet.
Riskier/ Unhealthy option #1 (use at your own risk): I had some decent luck using mini Nilla wafers (cut in 1/2s with each side soaked in antibiotic and then sandwiched together like a PB & J lol---certainly not the healthiest option, but if you need to get it into him, you may have to get "safely" inventive. This was back when I was giving mine meds for months for multiple issues and HAD to give them to her...or she would have died. These are far from ideal, but she did survive--- ask a professional though because your bird may be in a worse state or too tiny to do this safely---just depends.
Riskier/ Unhealthy option #2 (again, use at your own risk):
I have also used small segments of reduced sodium Alexia brand sweet-potato fries in the past--- they are organic and low enough in salt if you are only giving them a very small portion of the fry (in theory, anyway)...plus, they are baked ....But still, you don't want to give t multiple fries...think, 1/4 of a fry or so (maybe less depending on the size of your bird)...cut it down the middle when warm--inject it, smush it back together and then cross your fingers (again- probably should not use a whole dose, depending on the size of the bird, but try to keep food content as low as possible and dose as high as possible without your bird rejecting it- they need to eat it all, unless you know exactly how much of the med was wasted). Again- this was what I used when I was desperate-- definitely consult your vet and use healthier options BEFORE resorting to things like this...I normally wouldn't suggest it, but I have a very picky bird and she was very sick, so...desperate times...
Basically, you want to make sure that whatever you give them doesn't fill them up to the point that they waste meds, and doesn't taste so awful that they don't eat it (and waste it). You may have to give it in small increments- but they still need the full days dose, and call your vet to explain that there will be some waste (write down the ML wasted so that you can get more). Don't give more or less than prescribed on a given day, but you may run low toward the end of the course, which is why you have to let them know ahead of time to make sure they are okay with it.
