Avocado, Tuna and Marinated Onion Tostadas
5/5 - (1 vote)

Serves 2


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  • ½ to 1 red onion, sliced into thin rings
  • ½ tsp salt
  • ½ tsp sugar
  • ½ cup apple cider vinegar or rice vinegar
  • ½ cup water
  • ½ tsp crushed hot pepper flakes
  • 1 can of tuna in water, 184 g/6.5 oz, drained
  • Juice from 1 lime
  • ⅛ tsp salt
  • 4 corn tostadas (grilled, homemade or store bought corn tortillas)
  • 4 cherry tomatoes, quartered
  • 1 avocado, diced
  • Fresh cilantro
  • Fresh ground pepper
  • Lime quarters and hot sauce, to serve


  1. Rinse the onions with boiling water and drain.
  2. In a large, 1 L Mason jar, mix the salt, sugar, vinegar, water and hot pepper flakes. Add the rinsed onions and marinate at room temperature for at least 30 minutes.
  3. Mix the tuna and lime juice in a bowl, using a fork. Salt and pepper to taste, and adjust seasoning as desired.
  4. Distribute the tuna mixture evenly on the 4 tostadas. Garnish with cherry tomatoes, avocado, marinated onions and fresh cilantro. Add pepper and serve with lime quarters and hot sauce.