Preheat your oven to 425°F.
Arrange the corn tortilla rounds on a baking sheet. Spray or rub them with a bit of olive oil and sprinkle on some salt.
Bake in the preheated oven for 10 minutes or until they become crispy and golden brown.
If needed, after 10 minutes, flip them over and bake for another 2 minutes.
Once the tostadas are ready, let them cool slightly.
In a mixing bowl, combine tomato, onion, garlic, jalapeño, cilantro, lime, salt, and pepper, and mix well to combine.
Heat a skillet over medium-high heat. Add ground beef to pan, breaking it up with a spatula.
Cook until browned for about 5 minutes then lower heat to simmer and add the taco seasoning packet along with 3/4 cup of water. Simmer for 5-10 minutes allowing sauce to thicken then remove from heat.
In a small bowl, combine sour cream, lime juice, and salt. Mix well to combine.
To assemble your tostadas, spread a thin layer of the refried beans onto the tostada followed by about 2 tablespoons of the ground beef and a sprinkle of cheese.
Add about 1-2 tablespoons of the pico de gallo and top it off with a drizzle of the lime crema.
Enjoy your beef and bean tostadas immediately while still warm.