In a large bowl, combine imitation crab, tomatoes, onion, cilantro, lemon juice, and salt. Mix well. It is ok if some of the imitation crab start to fall apart. Taste and adjust with more lemon juice and salt if needed. Cover with plastic wrap and keep in the fridge for 20 minutes.
Meanwhile, preheat the oven to 200˚F (95˚C).
Place tostadas on a baking sheet, and bake in the oven for 3 minutes or until warm. Transfer the tostadas to serving plates. Scoop ceviche on a tostada and serve immediately.
Notes
This recipe is for 7 - 8 tostadas, which is enough to serve as dinner for 2 people. If you're serving this as appetizer, it's good for 7 - 8 people.
Tostada is a fried corn tortilla. Instead of coming in little triangles like tortilla chips, these are round just like a tortilla. Top them with all different kind of things and eat as whole. You can easily find them in grocery stores in a pack along with the regular tortillas. My go-to brand is Guerrero.
Tostada taste so much better after a quick toasting in the oven. It's a must for me.
Do not top the tostada with ceviche until the last moment before serving. Soggy tostada is not that good.