For the vinaigrette: Combine the cilantro, extra-virgin olive and canola oils, vinegar, garlic, sugar and 1/2 teaspoon of salt in a blender; puree until smooth. Taste, and add salt as needed. The yield should be about 3/4 cup.
For the salad: Line a plate with paper towels.
Pour the peanut oil into a large skillet over medium heat. Once that oil starts to shimmer, add 2 or 3 tortillas (or as many as will comfortably fit); fry them on each side until crisp and golden brown, 1 to 2 minutes. Lift each tortilla with tongs and let the excess oil drip off, then transfer it to the paper-towel-lined plate. Working in batches, repeat with the remaining tortillas. Let the tortillas cool, then break them into bite-size pieces.
Toss the tortilla pieces with the lettuce, black beans, scallions, feta, tomatoes and 1/2 cup of the vinaigrette in a large serving bowl. Add the remaining 1/4 cup of the vinaigrette if desired, or reserve for another use. Serve right away.
The low heat of the oven turns these tomatoes almost jammy, shriveling them and concentrating their flavor beautifully. The amount of time it takes depends greatly on the size and juiciness of the tomatoes, so for the least fuss, don't mix varieties or sizes. Left long enough, they'll start to get a little chewy around the edges, which makes a nice counterpoint to the moisture inside.
Other herbs and spices, particularly cinnamon and paprika, can be substituted for the cumin, if desired. Put the tomatoes on bread or crostini for bruschetta, served as part of an antipasto platter with mixed olives, cheese and smoked fish; or toss with hot pasta for an instant sauce.
The tomatoes can be refrigerated in an airtight container for up to 2 weeks or frozen in heavy-duty plastic freezer bags for up to six months. If your refrigerator is under 38 degrees, you can pack the tomatoes into glass jars, covered with olive oil, for several months.
Directions for Tomatoes
Preheat the oven to 200 degrees. Line a large rimmed baking sheet with aluminum foil or parchment paper; do not overlap.
Place the tomatoes, cut side up, on the baking sheet. Season on the cut side with salt and pepper to taste, then drizzle with olive oil. Sprinkle 1/2 teaspoon cumin on each tomato half. Bake for 8 to 12 hours, or until the tomatoes have collapsed and shriveled to about 1/4 inch thick; they should still be moist inside. Cool completely, then refrigerate in an airtight container.
NOTE: Toast the cumin seed in a dry skillet over medium heat for 1 or 2 minutes, shaking the pan to keep the cumin from burning. It should be fragrant. Cool slightly, then grind to a coarse powder in a spice grinder or mortar and pestle.