For the crust: Preheat oven to 375 degrees Fahrenheit. Grease a 14x4 inch rectangular tart pan with a removable bottom.
In a food processor, add cornmeal, almond meal, and salt. Pulse a few times to combine. Add butter pieces and pulse until mixture resembles a coarse meal. Add ice water, pulsing between each tablespoon until it starts to look like wet sand. With your fingers, pinch a bit of the mixture to make sure it holds together. If it doesn't, add more water a teaspoon at a time.
Transfer the dough to the prepared tart pan, and press in with your fingers. pressing it no more than halfway up the sides of the pan (a little less will lessen crumbling).
Bake for 15-17 minutes, until the crust starts to turn golden brown. Place on cooling rack when done.
For the filling: In a medium bowl, combine ricotta and most of basil, leaving a little aside to garnish the top of finished tart. Add salt and pepper to taste. When the tart crust has cooled completely, spread ricotta mixture into crust. Top with tomato slices. Garnish with remaining basil, olive oil, and salt and pepper.