For me, the answer is still a plant. Aloe Vera. I have a few Aloe plants but I have not used them on sunburns, what I use is a commercial formulation which is Aloe Gel, specifically for Sunburns. But if you have Fresh Aloe vera, that is probably the best.
Next time make sure you use a good sunblock and apply after a few hours, prevention is better than cure. Sunburn on lips can happen too, it hurts and inflamed by lips (like Angelina Jole, but I'm a guy so made me looks worse). So use sunblock lipbalm if you will be on or near water surface a long time. I got the burn from sailing for 3 days nonstop.
I'm dark skinned so I really seldom get sunburned, but I still use a high SPF sunblock anyway, coz my wife and family doesn't want me to be invisible at night
TTFN
Arvin