In a large skillet, cook the bacon over med heat until crisp; drain on paper towels.
Pour off the fat from the skillet and heat the pan over med heat.
Season the chicken with salt, pepper and cayenne, add to pan, partially cover and cook, turning once, until golden on both sides and jus cooked through about 10 minutes, let rest for 5 minutes, then thinly slice.
Meanwhile using a food processor, puree the avocado with lemon juice.
Transfer to a bowl, stir in the mayo, then season with salt and pepper.
Spread 1 tbls avocado mixture on each slice of toast.
Divide the chicken among 4 toast slices and top each with 1/4 of the bacon.
Cover each stack with a toast slice, avocado side down.
Spread more avocado on top, then layer each stack with some spinach, strawberries, red onion and one of the remaining toast slices.