My tip for tantrums is ignore, ignore and ignore.
I know it's very hard especially when they're public - distraction is also great aswell....'oh look did you see that big birdie? quick lets see if we can go and catch it' - lots of expression etc
try to ignore looks and comments from other people - apart from other mums who always give that sympathetic look which makes you realise you're not alone
Hope this helps. I know it's hard