Preheat oven or toaster oven to 350 F/180 C. Spray a baking sheet with non-stick spray.: As the oven warms up, you should feel a gentle wave of heat and maybe catch a faint metallic scent from the racks, which tells me it is ready. A properly preheated oven ensures the crust starts to set immediately when the slices hit the tray, preventing sogginess. I always give the oven the full time to reach temperature because placing coated tomatoes into an underheated oven can make them release moisture and become limp. One common mistake is skipping the spray and having parts stick, so apply an even layer of non stick spray or a thin brush of oil to avoid tearing the crust when turning.
Cut the tomatoes into slices about 1/2 inch thick. (We used the flat inner pieces and discarded the ends of the tomatoes with rounded edges.): When you slice, the sound should be a clean, soft snap rather than mush. Uniform thickness helps them bake evenly and gives a predictable interior texture, tender but not mushy. I trim rounded ends because they tend to roll or cook unevenly. A frequent error is slicing too thin, which makes them collapse, so aim for that steady 1/2 inch thickness and use a sharp knife for clean edges.
Beat the eggs in a small bowl. In another bowl, mix the almond flour and Old Bay Seasoning. Remove and save half of the almond flour mixture, so you can work with two batches.: The beaten eggs should look smooth and slightly frothy, indicating they will coat evenly. Mixing the almond flour and seasoning releases a citrusy aroma from the Old Bay blend, which hints at the finished flavor. Saving half of the mixture prevents cross contamination and keeps your second batch as fresh as the first. A common slip is overcrowding the bowls, which leads to clumping; use shallow bowls so each slice gets an even dredge.
One at a time, dip both sides of each tomato slice into the egg and then into the almond flour mixture, using the fork or your fingers to press the almond mixture on to the tomato slice so it sticks.: You will hear a soft pat as the coating adheres, and the almond layer should look evenly textured, not patchy. Pressing ensures the crumbs bind to the moisture of the eggs and the surface of the tomatoes , which creates a uniform crust. I prefer using a fork for neatness, but fingers work well for pressing the crumbs into place. Avoid oversaturating the slice in the egg wash because too much liquid prevents the almond flour from forming a cohesive crust.
Place each tomato on the baking sheet after it's coated with the almond flour mixture. (Don't worry if they aren't completely perfect; just work on getting each one coated with almond flour as much as you can.): As you lay them out, notice how each piece rests flat with a clear outline of the crust; this visual cue tells me they will brown evenly. Leave a bit of space so hot air circulates and you get even coloring. One trap is crowding the pan, which causes steaming and a soggy finish, so arrange them in a single layer.
Bake tomatoes 35-40 minutes, turning carefully once.: During baking you will see the almond coating shift to a light golden brown and smell a warm, toasty aroma. Turning halfway ensures both sides develop an even crust and prevents one side from overbrowning. The tomatoes should soften without collapsing, and juices may glisten at the edges. A mistake to avoid is flipping too soon while the crust is fragile, which can strip coating off, so wait until the underside seems set and golden before turning.
While the tomatoes bake, mix together the ranch dressing and Sriracha sauce to make the dipping sauce.: Whisking the ranch dressing and Sriracha Sauce releases a tangy aroma and creates a silky, pale pink sauce that clings nicely to the crust. Taste as you go so you can adjust the heat level. A common misstep is adding too much Sriracha at once, making the sauce overpowering, so start small and ramp up if you want more punch.
The baked tomatoes are done when the almond mixture is lightly browned on each side and tomatoes are cooked through. Serve hot.: When they are ready, the crust will be evenly colored, and the interior tomatoes will yield slightly under pressure but still retain shape. Serve immediately for the best contrast between crisp crust and warm, tender center. If you wait too long, steam can soften the crust, so plan to plate and dip soon after they come out.
I saved some of these to see how they would hold up to a night in the refrigerator. I reheated them about 15 minutes in a preheated toaster oven set on 450 F/230 C. Although they were best freshly made, I thought the reheated ones were surprisingly good.: After refrigeration, reheating in a hot toaster oven crisps the almond coating and revives some texture, and you will notice the aroma intensify as the oil in the crust warms. Reheating too long at high heat can dry the interior, so watch closely and pull them when the crust regains its crackle. A trap is using a microwave for reheating because it will make them soggy.