The idea that certain foods in any mom's diet will cause gas in her baby is incredibly persistent but is not founded in research. If certain foods in moms' diets were an overall problem for most babies, we would expect that cultures that emphasize those foods would have more gassy and fussy babies, but this does not occur at all.
This is not to say that certain foods would not bother a particular baby - this does happen occasionally (and it's more likely with very young babies). However, there is no list of foods that every mom should avoid while breastfeeding. In fact, most babies are fine with any food that mom eats, so there is no reason to avoid a food unless you notice an obvious reaction in your baby every time you eat a particular food.