If you want to make a great, easy, authentic Pad Thai, you need to try the She Simmers Pad Thai tutorial
Pad Thai Part One
Pad Thai Part Deux
Pad Thai Part Tres
Pad Thai Part Four
Pad Thai Part Five
How to handle Palm Sugar
How to make Tamarind paste - also how to identify the WRONG sorts of tamarind for Pad Thai
There is no peanut butter in Pad Thai. If you don't want to use tomatoes because they're not true to the original recipe, you won't want to use peanut butter, either. Try the above.
Some modifications I made include leaving out the little dried shrimp - sorry but I just don't want to eat shells and all of any sort of shell fish, and it worries me to think what's probably in the dye they use to turn the little buggers bright red. Besides, they're a bugger to find.
I tried it with the shrimp paste and didn't like it - too fishy. I just leave it out, whether or not that makes it less "authentic". YMMV.
I used about half the oil She Simmers swears is so necessary, actually less than that I think. That much oil was just way to much for my taste.
Follow her recipe and procedures very closely the first time. After that feel free to improvise. People in Thailand do.
BTW - do NOT get any sort of Korean fish sauce for these Thai dishes. Get Tiparos, Golden Boy (there's a picture of a baby in a diaper holding a bottle of fish sauce on it), 3 Crabs brand, which has a label trimmed in pink and a picture of 3 crabs and is actually Vietnamese but is frequently used for Thai food, or Squid brand - it says "Squid Brand" and has a picture of a squid on it. You could get Thai Kitchen brand but it's sort of expensive compared to the other brands when you find them in an ethnic grocery.
Make sure you have some lime wedges for squeezing over your completed dish, and Enjoy!