Heat oil in 10” non-stick skillet over medium heat. Add potatoes. Cook, turning occasionally, until potatoes are fork- tender, about 15 minutes (potatoes should not brown). Add onions to skillet. Cook, stirring occasionally, until onions turn soft and translucent and potatoes are fully cooked, about 10 minutes more. Carefully strain potatoes and onions into colander, reserving 1 tbsp. olive oil. Set aside potatoes until cool.
In bowl, whisk together eggs and Adobo. Stir in cooled potato- onion mixture until thoroughly combined.
In same skillet over low heat, heat reserved oil. Add egg-potato mixture. Cook, without stirring, until eggs begin to cook through and bottom begins to lightly brown, about 10 minutes. Carefully slide the tortilla onto flat plate. Invert another flat plate over the tortilla and turn upside down. Slide the tortilla back into the skillet cooked-side up.
Continue to cook tortilla until completely set, about 10 minutes. Slide onto serving plate. Serve warm or cold.