Have the homemade salt-only bacon already cooked and chopped. Remove stems and gills from 4–6 portobellos, keeping caps intact. Brush inside and outside with some juice from 1 lemon, sprinkle with salt and pepper, and set aside. These caps remain unheated.

Pulse the coarsely chopped 1/2 head cauliflower in the Ninja BN801 food-processor configuration with chopping blade, about 10–15 pulses of one second each, until the pieces look rice-size. Stop before a wet paste forms. Follow the appliance assembly/fill limits and work in batches if needed.

Melt 1/2 tablespoon coconut oil in a large frying pan over medium-high heat. Add the cauliflower, 3/4 cup finely sliced French artichoke hearts, finely chopped small zucchini, 2 cooked chopped bacon strips, 2 chopped small tomatoes, green parts of 4 green onions and minced garlic clove. If using dried basil instead of fresh, add 2 teaspoons now.

Stir frequently for about 3–5 minutes, until the vegetables are tender. Move the mixture from the edges and center. Keep the cauliflower grain-like; lower the heat if browning or catching happens before the vegetables soften, and use actual tenderness as the endpoint.

Take off the heat. Stir in optional 1/4 cup freshly grated pure Parmesan and 2 tablespoons fresh basil if using. Add a drizzle of the remaining lemon juice and salt and pepper to taste, accounting for the seasoning already in the cooked bacon.

Arrange the prepared caps hollow-side up on a plate and spoon the warm filling across them. Serve four portions, with firm unheated caps and tender filling. The 15-minute preparation and 5-minute cook estimate assumes bacon ready; curing/cooking bacon are separate. No oven or cap-roasting step.