As you turn into Valentin Navarro, a little alley off Calle Bustillos, you know you've come to the heartland of trout in La Paz. You can buy it fresh, or fried in the monstrous iron pans there in the street, or duck into El Acuario for a little-known regional treat, the wallake de trucha (trout). Most commonly cooked in the heights outside of La Paz around Lake Titicaca, this is the perfect dish to beat the effects of altitude that tend to weigh you down in La Paz. Trout, fresh from the lake, is boiled with potato, chuño (the freeze-dried potato so loved here), onion, garlic and a generous helping of chili and a green herb called coa (in Peru, muña) that has a sharp, refreshing, almost eucalyptus flavor. The soft, warm pink trout is a treat, while the bite of the chili and the coa, widely used to aid digestion, will leave you feeling great.