Bring a large pot of water to a boil. Salt the water and add pasta. Cook until al dente. Drain.
In a large pan, heat olive oil and 1 tablespoon butter over medium-high heat. Season shrimp with salt and pepper and sprinkle with cumin and paprika. Add shrimp to pan. Cook until pink on bottom and flip over. As soon as you get them flipped, add shallots and garlic. Then add tequila and carefully tilt the pan to ignite the tequila (if you have a gas stove). The flames can go pretty high so make sure your face is nowhere near the pan! Note: it's not necessary to light the tequila. Most of the alcohol will still burn off and it will taste pretty much the same.
Remove shrimp and set aside. Add chicken broth and simmer until reduced in half.
Add heavy cream, lime zest, and red pepper flakes and simmer 1 minute. Season sauce to taste with salt and pepper.
Add tomato and 2 tablespoons butter. Turn heat off, stir to incorporate the butter and add fettuccine and shrimp to pan. Toss to coat fettuccine.
Divide into serving bowls and top with avocado and cilantro.