Gluten-Free, Vegan, and Vegetarian are on the menu, but the same kitchen also prepares what you avoid, so cross-contamination is possible. Tell staff what you react to, and ask how your dish is prepared before you order.
Lechon is a South American wood fired grill on Naito Parkway in Portland. Its dinner menu marks most dishes gluten-free and the vegetarian ones V, and its FAQ mentions vegan options and a vegetarian menu. The menu itself says GF dishes may be cooked on the same surface as gluten, so the kitchen has the final word.