I keep running into a consistent problem in solo queue as an adc. Whenever the enemy team gets soraka, the lane always wins againsts me if the jungler doesnt gank or if mid doesnt gank. So my question is, what are some strategies for facing soraka in lane, assuming you cant get a healing reduction champ, and the enemy ad is someone strong like corki, ez, graves, assuming you get no gank assistance?

Kill soraka

Do it in burst.
(Graves Sona, Taric Graves etc.)

Note: Early on Soraka's heal is on a 20 seconds cooldown....and the amount is small...so make good use of that.

What champs are you playing adc? I'm sure someone way more experienced than me can help you with specifics.

I find it easier to burst when her heal is on cooldown or save your burst until AFTEr she uses her heal and attack the person she did not use it on.

Also if you focus your burst on soroka her armor/magic res is usually lower then the ADC

It's just a matter of coordination. Ping who you want to die, ignite them, then put on the deeps. (In that order, that's important.)

Of course, most ADC + Support lanes aren't exactly set up for to get kills, against Soraka or any other enemy champions. So the first step is to play something like Taric + Ezreal / Leona + Vayne / A champion that can do anything to begin with.

I am generally good at last hitting under pressure, but under those circumstances you'll want to stay clear of whatever harass they put out. If this means getting zoned, then that's when your jungler should come (but you said he doesn't, so you'll just have to wait until the enemy ADC pushes the lane). Last hitting under your turret has to be coordinated between you and your support unless you have enough AD to kill the creeps in one hit, but you can keep it at your tower for quite some time if the enemies aren't readily trying to pull it back. Just keep pinging for your jungler to come.

Mf and tristana counter soraka very hard, due to their healing reduction.

I'm agreeing with the majority of the thread here, once she does her early heal, you've got about 20 seconds providing something weird didn't happen like jungle invasion gave her your blue. If your support has a skillshot or, better yet, if you do, spam it at the bushes you know she's in. Sorakas are generally not going to move, because they'll assume you just did that to check or to scare them. If there's a ward in there, even better, because you'll be able to see her heal. Once she does that, have your support ready to help you bring down their carry. BUT. You need to remember she also has an under 10sec cooldown silence. This can easily screw up the last skill used to bring someone down, or can prevent your support from healing you in time. She's much slower than the carries early game, as she'll be building towards Philo stone instead of boots, so if it looks like the carry is going to get away, don't hesitate to turn your efforts over to her. Her first rank in ult also has about a 2 minute 40 second cooldown.
Finally, if your health is high enough, wait until her carry goes back. Soraka is easy to beat down on her own, even at her tower if you're careful. I've had many games where I've yelled at my computer "No no don't go back, I can't handle this many creeps on my own". Even with starcall, she's very low damage, but just make sure to do it while her heal is on cooldown

whenever I see a soraka I counter with leona. GG.

Get some hard cc support like taric or janna
Then you get ignite and Trist/cait = good harass, then jump in to finish off.