Adapted from https://thefeedfeed.com/wellness_arevik/fennel-pasta-salad
Heat grill to medium. Toss fennel with olive oil and salt and pepper. Cook on grill for 2-3 minutes per side, until fully cooked. Let cool, then thinly slice.
Meanwhile bring a large pot of salted water to a boil. Add pasta and cook according to package directions. Drain, then return to the same pot and add tomatoes and spinach. Cook over medium low heat until the spinach has wilted. Remove from heat, then add sliced fennel.
Blend avocado, lemon juice and salt and pepper in a high-speed blender until smooth. Add to the pasta and toss to coat.