Preheat smoker to 275°F.
Slice roma tomatoes into halves and remove seeds. Peel and cut onion in half.
Place tomatoes and onion onto fish and vegetable mat or in disposable aluminum tray and smoke for 40 minutes.
Remove from smoker and cool. Once cooled, chop roughly.
Cut each avocado lengthwise and remove seeds. Spoon out avocado flesh and place in medium bowl. Sprinkle with salt, pepper, lime juice, and zest.
Begin to mash with fork or hand mixer for a smoother consistency.
Add in smoked tomatoes, smoked onion, minced garlic, and chopped cilantro. Combine gently. Taste and adjust salt and lime to preference.
Cover bowl with plastic wrap and let chill for 30 minutes.
Serve with freshly fried corn chips seasoned with Tajin.